Vehicular signal mirror

ABSTRACT

A vehicular signal mirror includes a reflective mirror element comprising a mirror reflector on a light-transmitting substrate. The visible light reflectance is at least about 40% for visible light incident upon the front side of the reflective mirror element. A turn signal light display and/or a blind-spot indicator light display is disposed to the rear of the reflective mirror element and configured so that the light emitted by the light display passes through the reflective mirror element to be viewed by a viewer viewing from the front of the reflective mirror element. The light display exhibits, when electrically powered and when operated in the vehicle during day time driving conditions, a display luminance of at least about 30 foot lamberts as measured with the light display placed behind, and emitting light through, the reflective mirror element.

RELATED UNITED STATES PATENT APPLICATION

This application is a continuation of U.S. application Ser. No.11/655,096, filed Jan. 19, 2007, which is continuation of U.S.application Ser. No. 11/244,182, filed Oct. 6, 2005, which is acontinuation of U.S. application Ser. No. 10/971,456, filed Oct. 22,2004, now U.S. Pat. No. 7,004,592, which is a continuation of U.S.application Ser. No. 09/954,285, filed Sep. 18, 2001, now abandoned,which is a continuation of U.S. application Ser. No. 08/957,027, filedOct. 24, 1997, now abandoned, which is a continuation of U.S.application Ser. No. 08/429,643, filed Apr. 27, 1995, now U.S. Pat. No.5,724,187, which is a continuation-in-part of U.S. application Ser. No.08/238,521, filed May 5, 1994, now U.S. Pat. No. 5,668,663.

BACKGROUND OF THE INVENTION

1. Technical Field of the Invention

The present invention relates to electrochromic devices for continuouslyvarying the transmissivity to light suitable for use in, for example,electrochromic rearview mirrors, windows and sun roofs for motorvehicles, manufactured front electrochromic solid films and electrolytescontaining redox reaction promoters and alkali ions and/or protons.

2. Brief Description of the Related Technology

Prior to the introduction of electro-optic mirrors into the automotivemarketplace, prismatic rearview mirrors were available to drivers ofmotor vehicles to determine the whereabouts of neighboring motorvehicles to their rearward surroundings. By using a manual lever locatedon such mirrors, a driver of a motor vehicle, especially at dusk orlater, would be able to employ a prismatic feature on the mirror tovitiate the effect of headlamp glare (the principal source of incomingelectromagnetic radiation from the rear of the motor vehicle) from thelow beam, and especially high beam, lighting elements of other motorvehicles travelling posterior thereto. Should the lever be flipped tothe nighttime position, the driver would be able to view an image in areflection from a glass-to-air interface on the first surface of themirror. The light reflected from this first surface would exhibitnon-spectral selectivity. That is, the background of any image viewed inthe nighttime position of the prismatic mirror would be a neutral color.Such conventional prismatic mirrors are still used on a majority ofmotor vehicles in the United States today.

With the advent of electro-optic technology, such as electrochromictechnology, it has become possible to achieve continuous variability inreflectivity in rearview mirrors for motor vehicles. This continuousvariability has been achieved, for example, through the use ofreversibly variable electrochromic devices, wherein the intensity oflight (e.g., visible, infrared, ultraviolet or other distinct oroverlapping electromagnetic radiation) is modulated by passing the lightthrough an electrochromic medium. In such devices, the electrochromicmedium is disposed between two conductive electrodes and undergoeselectrochromism when potential differences are applied across the twoelectrodes.

Some examples of these prior art electrochromic devices are described inU.S. Pat. No. 3,280,701 (Donnelly); U.S. Pat. No. 3,451,741 (Manos);U.S. Pat. No. 3,806,229 (Schoot); U.S. Pat. No. 4,465,339 (Baucke); U.S.Pat. No. 4,712,879 (Lynam) (“Lynam I”); U.S. Pat. No. 4,902,108 (Byker)(“Byker I”); Japanese Patent Publication JP 57-30,639 (Negishi)(“Negishi I”); Japanese Patent Publication JP 57-208,530 (Negishi)(“Negishi II”); and I. F. Chang, “Electrochromic and ElectrochemichromicMaterials and Phenomena”, in Nonemissive Electrooptic Displays, 155-96,A. R. Kmetz and F. K. on Willisen, eds., Plenum Press, New York (1976).

Numerous devices using an electrochromic medium wherein theelectrochromism takes place entirely in a liquid solution are known inthe art [see e.g., U.S. Pat. No. 5,128,199 (Byker) (“Byker II”);Donnelly, Manos, Schoot and Byker I; and commonly assigned U.S. Pat. No.5,073,012 (Lynam) (“Lynam II”); U.S. Pat. No. 5,115,346 (Lynam) (“LynamIII”); U.S. Pat. No. 5,140,455 (Varaprasad) (“Varaprasad I”); U.S. Pat.No. 5,142,407 (Varaprasad) (“Varaprasad II”); U.S. Pat. No. 5,151,816(Varaprasad) (“Varaprasad III”); U.S. Pat. No. 5,239,405 (Varaprasad)(“Varaprasad IV”); and commonly assigned co-pending U.S. patentapplication Ser. Nos. 07/935,784 (filed Aug. 27, 1992), now U.S. Pat.No. 5,500,760, and Ser. No. 08/061,742 (filed May 17, 1993), now U.S.Pat. No. 5,424,865] Typically, these electrochromic devices, sometimesreferred to as electrochemichromic devices, are single-compartment,self-erasing, solution-phase electrochromic devices. See e.g., Manos,Negishi II, Byker I and Byker II.

In single-compartment, self-erasing, solution-phase electrochromicdevices, the intensity of the electromagnetic radiation is modulated bypassing through a solution of the color-forming species held in asingle-compartment. The color-changing reaction occurs only in thissolution-phase. That is, there is no solid material present in thedevices that has the color-changing reaction in it. During operation ofsuch devices, the solution of the color-forming species is liquid orfluid, although it may be gelled or made highly viscous with athickening agent, and the components of the solution do not precipitate.See e.g., Byker I and Byker II.

Numerous devices using an electrochromic medium wherein theelectrochromism occurs in a solid layer are also widely described in theart. Among such devices are those that employ electrochromic thin filmtechnology [see e.g., N. R. Lynam, “Electrochromic Automotive Day/NightMirrors”, SAE Technical Paper Series, 870636. (1987); N. R. Lynam,“Smart Windows for Automobiles”, SAE Technical Paper Series, 900419(1990); N. R. Lynam and A. Agrawal, “Automotive Applications ofChromogenic Materials”, Large Area Chromogenics: Materials & Devices forTransmittance Control, C. M. Lampert and C. G. Granquist, eds., OpticalEng'g Press, Washington (1990); C. M. Lampert, “Electrochromic Devicesand Devices for Energy Efficient Windows”, Solar Energy Materials, 11,1-27 (1984); Japanese Patent Document JP 58-30,729 (Kamimori) (“KamimoriI”); U.S. Pat. No. 3,521,941 (Deb); U.S. Pat. No. 3,807,832(Castellion); U.S. Pat. No. 4,174,152 (Giglia); U.S. Pat. No. Re. 30,835(Giglia); U.S. Pat. No. 4,338,000 (Kamimori) (“Kamimori II”); U.S. Pat.No. 4,652,090 (Uchikawa); U.S. Pat. No. 4,671,619 (Kamimori) (“KamimoriIII”); U.S. Pat. No. 4,702,566 (Tukude); Lynam I and commonly assignedU.S. Pat. No. 5,066,112 (Lynam) (“Lynam IV”) and U.S. Pat. No. 5,076,674(Lynam) (“Lynam V”)].

In thin film electrochromic devices, an anodic electrochromic layerand/or a cathodic electrochromic layer, each layer usually made frominorganic metal oxides or polymer films, may be separate and distinctfrom one another. In contrast to the single-compartment, self-erasing,solution-phase devices referred to supra, these thin film electrochromicdevices modulate the intensity of electromagnetic radiation by passingthrough the individual anodic electrochromic layer and/or cathodicelectrochromic layer.

In certain thin film electrochromic devices, a thin film layer of asolid electrochromic material, such as a tungsten oxide-type solid film,may be placed in contact with a liquid electrolyte containing redoxpromoters, such as ferrocene and iodide, and a solvent. See e.g.,Kamimori III. In these electrochromic devices, the intensity ofelectromagnetic radiation is primarily modulated by passing through thesolid electrochromic material. When dimmed to a colored state, thesetungsten oxide-type solid films typically dim to a blue-colored state.

Having grown accustomed to conventional prismatic rearview mirrors formotor vehicles, some consumers of motor vehicles may show a preferencefor rearview mirrors possessing substantial non-spectral selectivity.That is, some consumers may prefer mirrors which present a substantiallygray color when dimmed to a colored state; in other words, a mirror thatexhibits a viewing background comparable in spectral reflectivity tothat of conventional prismatic mirrors.

On another note, the reflective element of the mirror is oftenconstructed from silver and is typically situated on the rearmostsurface of the mirror. That is, the reflective element is placed on thesurface of a glass substrate farthest from that surface which firstcomes in contact with incident light. However, such placement hascertain disadvantages. For instance, double imaging is a recognizedproblem in such mirror construction. In addition, in its path toreaching the reflective element of the mirror, incident light must firstpass through each of the glass substrates of the mirror assembly.Therefore, in these mirror constructions, to achieve good opticalperformance, higher quality glass should be used for both substrates.Moreover, these mirror constructions typically require the use of a thinfilm transparent conductive electrode coating on the inward surface ofeach substrate in order to apply a potential to the electrochromicelement. Requiring each substrate of the mirror to be of such higherquality glass and the use of two such transparent conductive electrodesincreases material and production costs. Further, placement of thereflective element on the rearmost surface of the mirror requires anadditional manufacturing step, which also increases production costs.And, such placement increases material and production costs due tonecessary measures taken to protect the reflective element (typically, ahighly reflective material, such as silver or aluminum) againstenvironmental degradation, such as through the use of a paint or thelike. Frequently, lead-based paints have been used for this purpose,thereby presenting environmental concerns.

It has been suggested and attempts have been made to place thereflective element of the mirror, such as silver, on the inward facingsurface of the rear substrate so as to act as a conductive electrodecoating as well as a reflective element. See e.g., Donnelly, Negishi I,Byker I and Byker II. This configuration is plainly attractive since iteliminates the need for a separate transparent conductive coating on therear substrate, thereby reducing the cost of manufacture.

In order to function in the dual role of reflective element andconductive electrode, a coating must (1) be electrochemically stable soas not to degrade during operation of the device, (2) remain securelyadhered to the rear substrate to maintain the integrity of the device,and (3) be highly reflective so that the mirror as a whole will have anacceptable level of reflectance. However, no known mirror constructionmeets all of these requirements—for example silver, commonly used as thereflective element in conventional mirror constructions, is highlyreflective but is not electrochemically stable and is difficult toadhere to the surface of a glass substrate. Other materials, such asrhodium or Inconel, which have been used as a combined reflectiveelement and conducting electrode in prior art mirrors are notsufficiently reflective to provide a highly reflective electrochromicmirror. Perhaps for these reasons, the prior art suggestions andattempts have not resulted in any commercially successful electrochromicmirror in which a single coating is used as both reflective element andconducting electrode.

Electrochromic devices, such as those using a solid film electrochromicmaterial, like tungsten oxide, may also exhibit deleterious performancewhen exposed to ultraviolet radiation over prolonged periods of time(e.g., conditions typically encountered during outdoor weathering). Thisdeleterious performance may be linked to any of a variety of sources,including a potential propensity for photochromism to occur.

On yet another note, displays, indicia and sensors, such asphotosensors, motion sensors, cameras and the like, have heretofore beenincorporated into certain electrochromic mirror constructions [see e.g.,U.S. Pat. No. 5,189,537 (O'Farrell) and U.S. Pat. No. 5,285,060(Larson)]. In these constructions, the reflective element of the mirrorhas been locally removed to create a highly transmissive local window.However, such use of displays and the like positioned behind thereflective element of electrochromic mirrors has been limited. Onereason for this limited use is due to diminished rear vision capabilityin that portion of the reflective element of the mirror which has beenremoved. Moreover, the displays and the like known to date may bedistracting as well as aesthetically non-appealing to the driver and/orpassengers of motor vehicles insofar as they may be visible andobservable within the mirror mounted in the motor vehicles when in theinactivated state. In addition, the known methods of incorporating suchdisplays and the like into mirrors have been only partially successful,labor intensive and economically unattractive from a manufacturingstandpoint.

Further, although it has been suggested to use semi-transparentreflectors in rearview mirrors [see e.g., U.S. Pat. No. 5,014,167(Roberts) (“Roberts I”) and U.S. Pat. No. 5,207,492 (Roberts) (“RobertsII”)], previous attempts have included the use of dichroic reflectorswhich are complex to design and expensive to fabricate. Also, where useof metallic reflectors has been suggested [see e.g., U.S. Pat. No.4,588,267 (Pastore)], it has been in the context of conventional mirrorssuch as prismatic mirrors. These suggestions fail to recognize theproblems that must be overcome to provide a highly reflecting andpartially transmitting electrochromic rearview mirror.

Therefore, the need exists for an electrochromic mirror that providessubstantial non-spectral selectivity when dimmed to a colored state,akin to that exhibited by conventional prismatic mirrors when in thenighttime position, along with continuous variability in reflectivity,ease and economy of manufacture and enhanced outdoor weatheringresilience. It would also be desirable, particularly in this connection,to have an electrochromic mirror construction that reduces material andmanufacturing costs by employing as only one of its substrates a highquality glass as a substrate and also as only one of its electrodes athin film, substantially transparent conductive electrode coating. Inaddition, it would be desirable for a mirror to have display-on-demandcapability where a display could become activated to be viewed ondemand, and where the display is (1) aesthetically appealing and notdistracting in its inactivated state, and (2) is manufactured with easeand economy.

SUMMARY OF THE INVENTION

The present invention meets the needs expressed above concerning thedesirability of a substantially non-spectral selective electrochromicmirror by providing such an electrochromic mirror that exhibitssubstantially non-spectral selectivity in the form of a substantiallyneutral or neutral gray appearance when dimmed to a color state by theintroduction of an applied potential. The electrochromic element of thismirror comprises an electrochromic solid film and an electrolyte, whichitself comprises redox reaction promoters and alkali ions and/orprotons.

Another aspect of the present invention provides a commerciallypracticable electrochromic mirror having a novel construction. Morespecifically, this novel mirror construction provides a layer ofreflective material coated on the inward surface of the second substratewhich also serves as a conductive electrode coating. The layer ofreflective material is overcoated with an electrochromic solid film andmay also be undercoated to promote its adhesion to the substrate.

This construction employs a higher quality glass for only one of itssubstrates and employs for only that substrate made from a higherquality glass a conductive electrode coating that is substantiallytransparent. That is, the construction permits the use of (1) a lowerquality glass as the second or rearmost substrate while maintaining goodoptical performance in the mirror; (2) a higher resistance, and hencemore economical, conductive electrode coating for the first or frontmostsubstrate which is made from a higher quality glass; and (3) only onesubstantially transparent conductive electrode coating (to be used onthe inward surface of the first substrate made from a higher qualityglass), which further reduces material costs incurred in the manufactureof such mirrors.

In addition, the layer of reflective material in this novel constructionreduces further still the material and production costs associated withsuch mirrors since it serves the additional role of a conductiveelectrode coating thereby obviating manufacturing costs associated witha separate substantially transparent conductive electrode coating.Moreover, in this construction, the reflective element of the mirror islocated within, and protected by, the sealed cavity which forms theelectrochromic element of the mirror. The reflective element of themirror is thus protected from degradation through environmental exposurewithout having to resort to the use of protective materials, such aslead-based overcoating paints or the like. The novel construction ofthis electrochromic mirror also enhances the resistance of thereflective material to physical, chemical and/or electrochemicaldegradation.

Further, the construction so provided also reduces image separationwhich can lead to the recognized problem of double imaging.

In addition, another aspect of the invention provides an “on demanddisplay” for mirrors, as described hereinafter. The mirror constructionreferred to supra and described in detail hereinafter, facilitatesplacement of displays, indicia and sensors and the like behind themirror element so that they may be viewed as an “on demand display”.

As stated supra, the electrochromic mirrors of the present inventionexhibit a substantially gray appearance when dimmed to a colored stateupon the introduction of an applied potential. The coloring capabilityof these mirrors determines the extent to which glare may be reflectedfrom the mirrors. As with other electrochromic mirrors, this coloringcapability may be continuously varied by controlling the magnitude,duration and polarity of the applied potential introduced thereto. Theappearance of the substantially gray color may be appealing to consumerpreferences (especially to certain drivers of motor vehicles whichemploy these mirrors) and to commercial design and manufacture concernsby virtue of its substantial color neutrality relative to the color ofthe housing, casing, structure, machine, instrument or vehicle withwhich it is to be used. That is, even when dimmed to a colored state,the electrochromic mirrors of the present invention are oftenaesthetically complementary to the color of the other component(s) withwhich they are to be used.

The electrochromic mirrors of the present invention are suitable for useas electrochromic rearview mirrors (e.g., truck mirrors, interior andexterior mirrors for motor vehicles), architectural mirrors or specialtymirrors, like those useful in aeronautical, periscopic or dental andmedical applications.

In addition to electrochromic mirrors, electrochromic devices, such aselectrochromic glazings (e.g., architectural glazings, like those usefulin the home, office or other edifice; aeronautical glazings, such asthose which may be useful in aircraft; or vehicular glazings, forinstance, windows, like windshields, side windows and backlights, sunroofs, sun visors or shade bands); electrochromic optically attenuatingcontrast filters, such as contrast enhancement filters, suitable for usein connection with cathode ray tube monitors and the like;electrochromic privacy or security partitions; electrochromic solarpanels, such as sky lights; electrochromic information displays; andelectrochromic lenses and eye glass, may also benefit from that which isdescribed herein, especially where substantially non-spectral selectivecoloring is desired.

Thus, the present invention exemplifies an advance in the art that willbecome readily apparent and more greatly appreciated by a study of thedetailed description taken in conjunction with the figures which followhereinafter.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 depicts a spectral scan of percent reflectance versus wavelengthin nanometers of an electrochromic mirror according to the presentinvention when in its bleached state.

FIG. 2 depicts a spectral scan of percent reflectance versus wavelengthin nanometers of an electrochromic mirror according to the presentinvention when dimmed to a neutral colored state.

FIG. 3A depicts a perspective view of an electrochromic mirror—i.e., aninterior rearview automobile mirror—according to the present invention.

FIG. 3B depicts a cross-sectional view of the electrochromic mirror ofFIG. 3A.

FIG. 4 depicts another cross-sectional view of the electrochromic mirrorof FIGS. 3A and 3B.

FIG. 5 depicts a cross-sectional view of another electrochromic mirrorconstruction according to the present invention. In this construction, asecondary weather barrier 12 has been applied to the joint, at whichsealing means 5 joins substrates 2, 3.

FIG. 6 depicts a cross-sectional view of still another electrochromicmirror construction according to the present invention. This mirrorconstruction is similar to the mirror construction of FIG. 5, exceptthat an adhesion promoter 11 is coated between substrate 3 andconductive electrode coating 4′.

FIG. 7 depicts a cross-sectional view of yet another electrochromicmirror construction according to the present invention.

FIG. 8 depicts a perspective view of an electrochromic mirrorconstructed with an on demand display.

FIG. 9 depicts a cross-sectional view of an electrochromic mirrorconstructed with an on demand display using a glass cover sheet over thedisplay window in the mirror construction.

FIG. 10 depicts a cross-sectional view of another electrochromic mirrorconstructed with an on demand display.

FIGS. 11A, B and C depict the orientation of the substrates in differentconstructions of the electrochromic mirrors and electrochromic devicesof the present invention. FIG. 11A depicts a perpendicular displacementof the first substrate and the second substrate. FIG. 11B depicts alateral displacement and a perpendicular displacement of the firstsubstrate and the second substrate. FIG. 11C depicts an arrangement ofthe first substrate and the second substrate, wherein the dimensions ofthe length and width of the first substrate are slightly greater thanthose of the second substrate. In this arrangement, the peripheral edgeof the first substrate extends beyond the peripheral edge of the secondsubstrate.

FIG. 12 depicts a perspective view of an electrochromic mirrorconstructed with turn signal indicia.

FIG. 13 depicts a perspective view of a multi-radius electrochromicmirror according to the present invention.

FIGS. 14A and B depict cross-sectional views of electrochromic devices,which illustrate different seal constructions that may be employed inaccordance with the present invention.

FIG. 15 is a schematic diagram of a synchronous manufacturing processfor electrochromic mirrors according to the present invention.

FIG. 16 is a schematic diagram of a constant pressure control systemuseful for evaporative deposition of solid electrochromic films.

FIG. 17 is a plot of percent transmission versus wavelength for acontinuously variable intensity filter fixed to the glass of theelectrochromic window cell for voltages applied to the electrochromicmedium within the range of from about 0 volts to about 1.4 volts. InFIG. 17, solid curve X represents the percent transmission versuswavelength (nm) spectrum for a 600 nm medium-band interference filterhaving a bandwidth of about 40 nm. Curve A represents light transmissionthrough the band pass filter and the electrochromic window cell with nopotential applied. Curve B represents light transmission through theband pass filter and the electrochromic window cell at an appliedpotential of about 0.3 volts. Curve C represents light transmissionthrough the band pass filter and the electrochromic window cell at anapplied potential of about 0.5 volts. Curve D represents lighttransmission through the band pass filter and the electrochromic windowcell at an applied potential of about 0.8 volts. Curve E representslight transmission through the band pass filter and the electrochromicwindow cell at an applied potential of about 1.1 volts. And curve Frepresents light transmission through the band pass filter and theelectrochromic window cell at an applied potential of about 1.4 volts.

FIG. 18 depicts a sectional view of an electrochromic device employingan electrochromic polymeric solid film.

FIG. 19 depicts a perspective view of an electrochromic glazingassembly.

The depictions in these figures are for illustrative purposes only andare not drawn to scale. Unless otherwise indicated, in the followingdetailed description of the invention the element numbers discussed aredescriptive of like elements of all figures.

DETAILED DESCRIPTION OF THE INVENTION

In accordance with the teaching of the present invention, there areprovided electrochromic mirrors, such as electrochromic rearview mirrorsfor a motor vehicle. These mirrors are constructed from a firstsubstantially transparent substrate with a substantially transparentconductive electrode coating on its inward surface and a secondsubstrate, which may or may not be substantially transparent, with aconductive electrode coating, which also may or may not be substantiallytransparent, on its inward surface. Whether the second substrate and theconductive electrode coating thereon are or are not substantiallytransparent will depend on the particular construction of the mirror.

The first substrate and second substrate may be positioned inspaced-apart relationship with one another, being substantially parallelor substantially tangentially parallel depending upon whether thesubstrates are flat or bent. These substrates may also be laterallydisplaced from, or in a substantially flush relationship with, oneanother. The substrates may also have respective dimensions such thatone of the substrates is sized and shaped to have a slightly greaterlength and width than the other substrate. Thus, when the substrates arepositioned in central alignment with one another, the peripheral edgesof the slightly larger substrate extend beyond the peripheral edges ofthe slightly smaller substrate.

The mirrors have a layer of reflective material coated either onto (a)the rearmost (non-inward) surface of the second substrate, where itserves a single role as a reflective element of the mirror or (b) theinward surface of the second substrate, where it serves a dual role as aconductive electrode coating and a reflective element of the mirror.

In these mirrors, an electrochromic solid film is coated either onto (a)the transparent conductive electrode coating of the first substrate, (b)the layer of reflective material when acting as a conductive electrodecoating on the inward surface of the second substrate or (c) thesubstantially transparent conductive electrode coating on the inwardsurface of the second substrate, when the layer of reflective materialis placed on the rearmost (non-inward) surface of the second substrate.

A sealing means is positioned toward the peripheral edge of each of thefirst substrate and the second substrate to form a cavity, in which islocated, either in a liquid-phase or a solid-phase, an electrolytecomprising redox reaction promoters and alkali ions and/or protons. Inthe cavity, the electrolyte is in contact with the electrochromic solidfilm (which itself is in contact with a conductive electrode coating onthe inward surface of one of either the first substrate or secondsubstrate) and a conductive electrode coating (on the inward surface ofthe other of the first substrate or second substrate) to form anelectrochromic element.

Finally, a means for introducing an applied potential to theelectrochromic element is also provided to controllably vary the amountof light reflected from the mirror.

Decreased light transmissivity in the electrochromic devices of thepresent invention (and reflectivity in the electrochromic mirrors) isprimarily provided by the color-forming reaction that occurs in theelectrochromic solid film. This electrochromic solid film may be a thinfilm layer of an inorganic transition metal oxide. Stoichiometric andsubstoichiometric forms of transition metal oxides, such as Group IV-B,V-B or VI-B oxides like tungsten oxide, molybdenum oxide, niobium oxide,vanadium oxide, titanium dioxide and combinations thereof, may be used.Other conventional inorganic transition metal oxides, such as thoserecited in Kamimori III, may also be employed. Preferably, however,tungsten oxide or doped tungsten oxide, with suitable dopants includingmolybdenum, rhenium, tin, rhodium, indium, bismuth, barium, titanium,tantalum, niobium, copper, cerium, lanthanum, zirconium, zinc, nickel,and the like, may be used as the electrochromic solid film. A beneficialeffect of the addition of the dopant may be to move the spectralabsorption edge of the doped tungsten oxide coating farther into thevisible range of the electromagnetic spectrum.

Where doped tungsten oxide is used, the dopant should be present in aconcentration within the range of from about 0.1% (by mole) to about 20%(by mole) or even greater. Preferred doped tungsten oxides include thosewhere a molybdenum dopant is used within the range of about 0.5% (bymole) to about 10% (by mole).

The electrochromic solid film may be a stack of thin films, such as alayer of tungsten oxide overcoated and/or undercoated with a thin filmlike silicon dioxide, titanium dioxide, tantalum pentoxide or ceriumoxide. Such overcoats and/or undercoats may help promote enhancedadhesion of the tungsten oxide electrochromic solid film to itssubstrate and/or passivate it from the electrolyte which it contacts inthe electrochromic element.

When the electrochromic solid film comprises a stack of thin films, thelayers of the multiple layer stack may individually comprise anelectrochromic material. For example, a stacked electrochromic solidfilm can be formed by coating an electrochromic layer of molybdenumoxide onto a transparent conductor coated substrate (to a thickness of,for example, about 100 Å to about 3,000 Å), and by overcoating (and/orundercoating) the molybdenum oxide electrochromic layer with anotherelectrochromic solid film layer, such as tungsten-oxide having athickness, for example, in the range of about 100 Å to about 5,000 Å.Alternatively, multiple layers of tungsten oxide and layers ofmolybdenum oxide can be used to form a stacked electrochromic solidfilm.

When evaporating molybdenum oxide, it may be useful to melt-process themolybdenum oxide powder prior to evaporation. Since molybdenum oxidemelts at about 795° C., molybdenum oxide powder (typically about 100mesh) may be placed into a suitable high temperature resistant, inertevaporation crucible (such as an alumina crucible) and converted to asolid mass by heating to a temperature within the range of about 850° C.to about 900° C. for a period of time of about 60 minutes in a hightemperature furnace, preferably in an inert atmosphere such as anitrogen atmosphere. Since molybdenum oxide melts at a lower temperature(less than about 1,000° C.) compared to other electrochromic metaloxides such as tungsten oxide that melt at a temperature greater thanabout 1,000° C., molybdenum oxide (and equivalent lower melting metaloxides) may be used as a binder for evaporation of high melt temperaturemetal oxide powders.

The thickness of the electrochromic solid film may be within the rangeof from about 0.05 μm to about 1.0 μm or greater, with about 0.25 μm toabout 0.75 μm being preferred, and about 0.3 μm to about 0.6 μm beingmore preferred.

The electrochromic solid film may have a microstructure that isamorphous, crystalline, polycrystalline or combinations thereof. Inelectrochromic devices where the occurrence of photochromism is aconcern, it may be desirable for the electrochromic solid film topossess a microstructure that is at least partially crystalline. Such acrystalline microstructure is believed to minimize the photochromiceffect, which may be deleterious to the operation of the electrochromicdevices. It may also be desirable for the electrochromic solid film topossess a microstructure that is porous. In this connection, it may bedesirable for the electrochromic solid film, such as tungsten oxide ordoped tungsten oxide, to have a density of less than about 90%,preferably less than about 80%, of the density of the bulk oxide.

The electrolyte useful in the electrochromic element of theelectrochromic mirrors of the present invention should comprise redoxreaction promoters, and alkali ions and/or protons. The electrolyte maybe in a liquid-phase or in a solid-phase.

The redox reaction promoters of the electrolyte comprise two individualspecies, a metallocene and a phenothiazine used in combination.

The metallocenes suitable for use as a redox reaction promoter in thepresent invention are represented by the following structure:

wherein R and R₁ may be the same or different, and each may be selectedfrom the group consisting of H; any straight- or branched-chain alkylconstituent having from about 1 carbon atom to about 8 carbon atoms,such as CH₃, CH₂CH₃, CH₂CH₂CH₃, CH₃(CH₃)₂, C(CH₃)₃ and the like; acetyl;vinyl; allyl; hydroxyl; carboxyl; —(CH₂)_(n)—OH, wherein n may be aninteger in the range of 1 to about 8; —(CH₂)_(n)—COOR₂, wherein n may bean integer in the range of 1 to about 8 and R₂ may be any straight- orbranched-chain alkyl constituent having from about 1 carbon atom toabout 8 carbon atoms, hydrogen, lithium, sodium,

wherein n′ may be an integer in the range of 2 to about 8, or

wherein n′ may be an integer in the range of 2 to about 8;—(CH₂)_(n)—OR₃, wherein n may be an integer in the range of 1 to about 8and R₃ may be any straight- or branched-chain alkyl constituent havingfrom about 1 carbon atom to about 8 carbon atoms,

or —(CH₂)_(n)—N⁺(CH₃)₃X⁻, wherein n may be an integer in the range of 1to about 8 and X may be Cl⁻, Br⁻, I⁻, ClO₄ ⁻ or BF₄ ⁻; and

-   -   Me is Fe, Ni, Ru, Co, Ti, Cr and the like.

The phenothiazines suitable for use as a redox reaction promoter in thepresent invention include, but are not limited to, those represented bythe following structure:

wherein R₄ may be selected from the group consisting of H; any straight-or branched-chain alkyl constituent having from about 1 carbon atom toabout 10 carbon atoms; phenyl; benzyl; —(CH₂)₂—CN; —(CH₂)₂—COOH;

wherein n′ may be an integer in the range of 2 to about 8;

wherein R₂ may be any straight- or branched-chain alkyl constituenthaving from about 1 carbon atom to about 8 carbon atoms; and

-   -   R₅, R₆, R₇, R₈, R₉, R₁₀, R₁₁, R₁₂ may be selected from H, Cl,        Br, CF₃, CH₃, NO₂, COOH,

-   -   R₄ and R₁₂, when taken together, form a ring with six atoms        (five of which being carbon) having a carbonyl substituent on        one of the carbon atoms.

Preferred among phenothiazines II is phenothiazine III, as depicted inthe following structure:

Other desirable phenothiazines II include:

An example of a desirable quinone for use as a redox promoter in thepresent invention is

Combinations of redox reaction promoters may be selectively chosen toachieve a desired substantially non-spectral selectivity when theelectrochromic element (and the mirror in which the electrochromicelement is to function) is dimmed to a colored state.

The redox reaction promoters may be present in the electrolyte in atotal concentration of about 0.005 M to about 0.5 M, with a totalconcentration of about 0.02 M to about 0.1 M being preferred. The ratioof this combination (i.e., total metallocene to total phenothiazine)should be within the range of about 1:1 to about 1:10, with a preferredcombination of redox reaction promoters being ferrocene andphenothiazine (III) in about a 1:2 (by mole) to about a 1:4 (by mole)ratio and, more preferably, having a total concentration of about 0.07 Mto about 0.09 M.

A source of alkali ions may also be included in the electrolyte.Suitable sources of alkali ions are lithium salts, such as lithiumperchlorate (“LiClO₄”), lithium tetrafluoroborate (“LiBF₄”), lithiumiodide (“LI”), lithium hexafluorophosphate (“LiPF₄”), lithiumhexafluoroarsenate (“LiAsF₆”), lithium styrylsulfonate (“LiSS”), lithiumtriflate (“LiCF₃SO₃”); lithium methacrylate, lithium halides other thanLI, such as lithium chloride (“LiCl”), lithium bromide (“LiBr”) and thelike, lithium trifluoroacetate (“CF₃COOLi”) and combinations thereof. Ofthese, LiClO₄ or combinations of LiClO₄ and LiBF₄ are preferred. Thesesources of alkali ions may be present in the electrolyte in aconcentration of about 0.01 M to about 1.0 M, with a concentration ofabout 0.05 M to about 0.1 M being preferred.

A source of protons may also be included in the electrolyte, by, forexample, incorporating into the electrolyte water [for example, in aconcentration of less than about 5% (v/v), preferably in a concentrationwithin the range of about 0.5% (v/v) to about 2% (v/v)], or byincorporating into the electrolyte organic acids, inorganic acids orother protonic sources suitable for use in conjunction with organicsolvents as are known in the art.

The electrolyte itself may be in a liquid-phase or a solid-phase,however, where the electrolyte is in a liquid-phase, a suitable solventfor use in the electrolyte may solubilize the redox reaction promotersand alkali ions (and other optional components such as ultravioletstabilizing agents which absorb and/or screen ultraviolet radiation)while remaining substantially inert thereto (as well as to any otheroptional components in the electrolyte). Any material that remains inits liquid form over the range of temperatures to which the devicesmanufactured with the electrolytes of the present invention will likelybe subjected is suitable for use as a solvent in a liquid-phaseelectrolyte [for a non-exhaustive recitation of such solvents, see e.g.,Varaprasad I and Varaprasad III]. Practically speaking, the solvent maybe an organic solvent, preferably a substantially non-aqueous organicsolvent, which is stable to electrolysis and other phenomena likely tobe encountered during the practice of this invention.

Suitable solvents may be selected from acetonitrile,3-hydroxypropionitrile, methoxypropionitrile, 3-ethoxypropionitrile,2-acetylbutyrolactone, propylene carbonate, ethylene carbonate,glycerine carbonate, tetramethylene sulfone, cyanoethyl sucrose,γ-butyrolactone, 2-methylglutaronitrile, N,N′-dimethylformamide,3-methylsulfolane, glutaronitrile, 3,3′-oxydipropionitrile, methylethylketone, cyclopentanone, cyclohexanone, benzoyl acetone,4-hydroxy-4-methyl-2-pentanone, acetophenone, 2-methoxyethyl ether,triethylene glycol dimethyl ether, 4-ethenyl-1,3-dioxalane-2-one,1,2-butylene carbonate, glycidyl ether carbonates (such as thosecommercially available from Texaco Chemical Company, Austin, Tex.) andcombinations thereof, preferred of which include propylene carbonate,1,2-butylene carbonate, the combination of tetramethylene sulfone andpropylene carbonate and the combination of 1,2-butylene carbonate andpropylene carbonate.

Where the electrolyte of the present invention is desirably asolid-phase electrolyte, a formulation of starting components may be insitu transformed such as by polymerization reaction through, forinstance, exposure to ultraviolet radiation or application of thermalenergy, to produce a solid electrolyte. In the context of ultravioletradiation activated polymerization, ultraviolet polymerizable components[such as those taught by and described in commonly assigned co-pendingU.S. patent application Ser. No. 08/023,675, filed Feb. 26, 1993 (nowabandoned) (“the '675 application”) and Ser. No. 08/193,557, filed Feb.8, 1994 (now abandoned)(“the '557 application”), the disclosures of eachof which are incorporated herein by reference] may be used to transforminto a solid-phase electrolyte when exposed to ultraviolet radiation. Inaccordance with the disclosure of U.S. patent application Ser. No.08/193,557, filed Feb. 8, 1994 (now abandoned) (“the '557 application”),polychromic solid films may be prepared by exposing an electrochromicmonomer composition to electromagnetic radiation for a time sufficientto transform the electrochromic monomer composition into a polychromicsolid film. This in situ curing process initiates polymerization of, andtypically completely polymerizes, an electrochromic monomer composition,normally in a liquid state, by exposure to electromagnetic radiation toform a polychromic solid film, whose surface and cross-sections aresubstantially tack-free.

The electrochromic monomer compositions are comprised of anodicelectrochromic compounds, cathodic electrochromic compounds, each ofwhich are organic or organometallic compounds, a monomer component and aplasticizer. In addition, cross-linking agents, photoinitiators,photosensitizers, ultraviolet stabilizing agents, electrolyticmaterials, coloring agents, spacers, anti-oxidizing agents, flameretarding agents, heat stabilizing agents, compatibilizing agents,adhesion promoting agents, coupling agents, humectants and lubricatingagents and combinations thereof may also be added. In the preferredelectrochromic monomer compositions, the chosen monomer component may bea polyfunctional monomer, such as a difunctional monomer, trifunctionalmonomer, or a higher functional monomer, or a combination ofmonofunctional monomer and difunctional monomer or monofunctionalmonomer and cross-linking agent. Those of ordinary skill in the art maychoose a particular monomer component or combination of monomercomponents from those recited in view of the intended application so asto impart the desired beneficial properties and characteristics to thepolychromic solid film. To prepare a polychromic solid film, a monomershould be chosen as a monomer component that is capable of in situcuring through exposure to electromagnetic radiation, and that iscompatible with the other components of the electrochromic monomercomposition at the various stages of the in situ curing process. Thecombination of a plasticizer with a monomer component (with or withoutthe addition of a difunctional monomer or a cross-linking agent) shouldpreferably be in an equivalent ratio of between 75:25 to 10:90 toprepare polychromic solid films with superior properties andcharacteristics. Of course, the art-skilled should bear in mind that theintended application of a polychromic solid¹ film will often dictate itsparticular properties and characteristics, and that the choice andequivalent ratio of the components within the electrochromic monomercomposition may need to be varied to attain a polychromic solid filmwith the desired properties and characteristics.

Among the monomer components that may be advantageously employed in U.S.patent application Ser. No. 08/193,557, filed Feb. 8, 1994 (nowabandoned) (“the '557 application”) are monomers having at least onereactive functionality rendering the compound capable of polymerizationor further polymerization by an addition mechanism, such as vinylpolymerization or ring opening polymerization. Included among suchmonomers are oligomers and polymers that are capable of furtherpolymerization. For monomers suitable for use herein, see generallythose commercially available from Monomer-Polymer Labs., Inc.,Philadelphia, Pa.; Sartomer Co., Exton, Pa.; and Polysciences, Inc.,Warrington, Pa.

Monomers capable of vinyl polymerization, suitable for use herein, haveas a commonality the ethylene functionality, as represented below:wherein R₆, R₇ and R₈ may be the same or different, and are eachselected from a member of the group consisting of hydrogen; halogen;alkyl, cycloalkyl, poly-cycloalkyl, heterocycloalkyl and alkyl andalkenyl derivatives thereof; alkenyl, cycloalkenyl, cycloalkadienyl,poly-cycloalkadienyl and alkyl and alkenyl derivatives thereof;hydroxyalkyl; hydroxyalkenyl; alkoxyalkyl; alkoxyalkenyl; cyano; amido;phenyl; benzyl and carboxylate, and derivatives thereof.

Preferred among these vinyl monomers are the ethylene carboxylatederivatives known as acrylates—i.e., wherein at least one of R₆, R₇ andR₈ are carboxylate groups or derivatives thereof. Suitable carboxylatederivatives include, but are not limited to alkyl, cycloalkyl,poly-cycloalkyl, heterocycloalkyl and alkyl and alkenyl derivativesthereof; alkenyl, cycloalkenyl, poly-cycloalkenyl and alkyl and alkenylderivatives thereof; mono- and poly-hydroxyalkyl; mono- andpoly-hydroxyalkenyl; alkoxyalkyl; alkoxyalkenyl and cyano.

Among the acrylates that may be advantageously employed herein are mono-and poly-acrylates (bearing in mind that poly-acrylates function ascross-linking agents as well, see infra), such as 2-hydroxyethylacrylate, 2-hydroxyethyl methacrylate, methylene glycol monoacrylate,diethylene glycol monomethacrylate, 2-hydroxypropyl acrylate,2-hydroxypropyl methacrylate, 3-hydroxypropyl acrylate, 3-hydroxypropylmethacrylate, dipropylene glycol monomethacrylate, 2,3-dihydroxypropylmethacrylate, methyl acrylate, ethyl acrylate, n-propyl acrylate,i-propyl acrylate, n-butyl acrylate, s-butyl acrylate, n-pentylacrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethylmethacrylate, n-propyl methacrylate, i-propyl methacrylate, n-butylmethacrylate, s-butyl methacrylate, n-pentyl methacrylate, s-pentylmethacrylate, methoxyethyl acrylate, methoxyethyl methacrylate,triethylene glycol monoacrylate, glycerol monoacrylate, glycerolmonomethacrylate, allyl methacrylate, benzyl acrylate, caprolactoneacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, 2-ethoxyethylacrylate, 2-ethoxyethyl methacrylate, 2-(2-ethoxyethoxy)ethylacrylate,glycidyl methacrylate, n-hexyl acrylate, n-hexyl methacrylate, isobornylacrylate, isobornyl methacrylate, i-decyl acrylate, i-decylmethacrylate, i-octyl acrylate, lauryl acrylate, lauryl methacrylate,2-methoxyethyl acrylate, n-octyl acrylate, 2-phenoxyethyl acrylate,2-phenoxyethyl methacrylate, stearyl acrylate, stearyl methacrylate,tetrahydrofurfuryl acrylate, tetrahydrofurfuryl methacrylate, tridecylmethacrylate, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate,1,3-butylene glycol diacrylate, 1,3-butylene glycol dimethacrylate,diethylene glycol diacrylate, diethylene glycol dimethacrylate, ethyleneglycol diacrylate, ethoxylated bisphenol A dimethacrylate, ethyleneglycol dimethacrylate, 1,6-hexanediol diacrylate, 1,6-hexanedioldimethacrylate, neopentyl glycol diacrylate, neopentyl glycoldimethacrylate, polyethylene glycol diacrylate, polyethylene glycoldimethacrylate, tetraethylene glycol diacrylate, tetraethylene glycoldimethacrylate, triethylene glycol diacrylate, triethylene glycoldimethacrylate, tripropylene glycol diacrylate, dipentaerythritolpentaacrylate, ethoxylated pentaerythritol triacrylate, pentaerythritoltetraacrylate, pentaerythritol triacrylate, trimethylolpropanetriacrylate, trimethylolpropane trimethacrylate,tris(2-hydroxyethyl)-isocyanurate triacrylate,tris(2-hydroxyethyl)-isocyanurate trimethacrylate, polyethylene glycolmonoacrylate, polyethylene glycol monomethacrylate, polypropylene glycolmonoacrylate, polypropylene glycol monomethacrylate, hydroxyethylcellulose acrylate, hydroxyethyl cellulose methacrylate, methoxypoly(ethyleneoxy)ethylacrylate, methoxypoly(ethyleneoxy)ethylmethacrylate and combinations thereof. For afurther recitation of suitable acrylates for use herein, see thoseacrylates available commercially from Monomer-Polymer Labs, Inc.;Polysciences, Inc. and Sartomer Co. Also, those of ordinary skill in theart will appreciate that derivatized acrylates in general should providebeneficial properties and characteristics to the resulting polychromicsolid film.

Other monomers suitable for use herein include styrenes, unsaturatedpolyesters, vinyl ethers, acrylamides, methyl acrylamides and the like.

Monomers capable of ring opening polymerization suitable for use hereininclude epoxides, lactones, lactams, dioxepanes, spiro orthocarbonates,unsaturated spiro orthoesters and the like.

Preferred among these ring opening polymerizable monomers are epoxidesand lactones. Of the epoxides suitable for use herein, preferred arecyclohexene oxide, cyclopentene oxide, glycidyl i-propyl ether, glycidylacrylate, furfuryl glycidyl ether, styrene oxide, ethyl-3-phenylglycidate, 1,4-butanediol glycidyl ether,2,3-epoxypropyl-4-(2,3-epoxypropoxy)benzoate,4,4′-bis-(2,3-epoxypropoxy)biphenyl and the like.

Also, particularly preferred are the cycloalkyl epoxides sold under the“CYRACURE” tradename by Union Carbide Chemicals and Plastics Co., Inc.,Danbury, Conn., such as the “CYRACURE” resins UVR-6100 (mixed cycloalkylepoxides), UVR-6105 (3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate), UVR-6110 (3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate) and UVR-6128 [bis-(3,4-epoxycyclohexyl)adipate], and the“CYRACURE” diluents UVR-6200 (mixed cycloalkyl epoxides) and UVR-6216(1,2-epoxyhexadecane); those epoxides commercially available from DowChemical Co., Midland, Mich., such as D. E. R. 736 epoxy resin(epichlorohydrin-polyglycol reaction product), D.E.R. 755 epoxy resin(diglycidyl ether of bisphenol A-diglycidyl ether of polyglycol) andD.E.R. 732 epoxy resin (epichlorohydrin-polyglycol reaction product),and the NOVOLAC epoxy resins such as D.E.N. 431, D.E.N. 438 and D.E.N.439 (phenolic epoxides), and those epoxides commercially available fromShell Chemical Co., Oak Brook, Ill., like the “EPON” resins 825 and1001F (epichlorohydrin-bisphenol A type epoxy resins).

Other commercially available epoxide monomers that are particularlywell-suited for use herein include those commercially available underthe “ENVIBAR” tradename from Union Carbide Chemicals and Plastics Co.,Inc., Danbury, Conn., such as “ENVIBAR” UV 1244 (cycloalkyl epoxides).

In addition, derivatized urethanes, such as acrylated (e.g., mono- orpoly-acrylated) urethanes; derivatized heterocycles, such as acrylated(e.g., mono- or polyacrylated) heterocycles, like acrylated epoxides,acrylated lactones, acrylated lactams; and combinations thereof, capableof undergoing addition polymerizations, such as vinyl polymerizationsand ring opening polymerizations, are also well-suited for use herein.

Many commercially available ultraviolet curable formulations arewell-suited for use herein as a monomer component in the electrochromicmonomer composition. Among those commercially available ultravioletcurable formulations are acrylated urethanes, such as the acrylatedalkyl urethane formulations commercially available from Sartomer Co.,including Low Viscosity Urethane Acrylate (Flexible) (CN 965), LowViscosity Urethane Acrylate (Resilient) (CN 964), Urethane Acrylate (CN980), Urethane Acrylate/TPGDA (CN 966 A80), Urethane Acrylate/IBOA (CN966 J75), Urethane Acrylate/EOEOEA (CN 966H90), Urethane Acrylate/TPGDA(CN 965 A80), Urethane Acrylate/EOTMPTA (CN 964 E75), UrethaneAcrylate/EOEOEA (CN 966H90), Urethane Acrylate/TPGDA (CN 963 A80),Urethane Acrylate/EOTMPTA (CN 963 E75), Urethane Acrylate (Flexible) (CN962), Urethane Acrylate/EOTMPTA (CN 961 E75), Urethane Acrylate/EOEOEA(CN 961H90), Urethane Acrylate (Hard) (CN 955), Urethane Acrylate (Hard)(CN 960) and Urethane Acrylate (Soft) (CN 953), and acrylated aromaticurethane formulations, such as those sold by Sartomer Co., may also beused herein, including Hydrophobic Urethane Methacrylate (CN 974),Urethane Acrylate/TPGDA (CN 973 A80), Urethane Acrylate/IBOA (CN 973J75), Urethane Acrylate/EOEOEA (CN 973H90), Urethane Acrylate (Flexible)(CN 972), Urethrane Acrylate (Resilient) (CN 971), UrethaneAcrylate/TPGDA (CN 971 A80), Urethane Acrylate/TPGDA (CN 970 A60),Urethane Acrylate/EOTMPTA (CN 970 E60) and Urethane Acrylate/EOEOEA (CN974H75). Other acrylated urethane formulations suitable for use hereinmay be obtained commercially from Monomer-Polymer Labs, Inc. andPolysciences, Inc.

Other ultraviolet curable formulations that may be used herein are theultraviolet curable acrylated epoxide formulations commerciallyavailable from Sartomer Co., such as Epoxidized Soy Bean Oil Acrylate(CN 111), Epoxy Acrylate (CN 120), Epoxy Acrylate/TPGDA (CN 120 A75),Epoxy Acrylate/HDDA (CN 120 B80), Epoxy Acrylate/TMPTA (CN 120 C80),Epoxy Acrylate/GPTA (CN 120 D80), Epoxy Acrylate/Styrene (CN 120 S85),Epoxy Acrylate (CN 104), Epoxy Acrylate/GPTA (CN 104 D80), EpoxyAcrylate/HDDA (CN 104 B80), Epoxy Acrylate/TPGDA (CN 104 A80), EpoxyAcrylate/TMPTA (CN 104 C75), Epoxy Novolac Acrylate/TMPTA (CN 112 C60),Low Viscosity Epoxy Acrylate (CN 114), Low Viscosity EpoxyAcrylate/EOTMPTA (CN 114 E80), Low Viscosity Epoxy Acrylate/GPTA (CN 114D75) and Low Viscosity Epoxy Acrylate/TPGDA (CN 114 A80).

In addition, “SARBOX” acrylate resins, commercially available fromSartomer Co., like Carboxylated Acid Terminated (SB 400), CarboxylatedAcid Terminated (SB 401), Carboxylated Acid Terminated (SB 500),Carboxylated Acid Terminated (SB 500E50), Carboxylated Acid Terminated(SB 500K60), Carboxylated Acid Terminated (SB 501), Carboxylated AcidTerminated (SB 510E35), Carboxylated Acid Terminated (SB 520E35) andCarboxylated Acid Terminated (SB 600) may also be advantageouslyemployed herein.

Also well-suited for use herein are ultraviolet curable formulationslike the ultraviolet curable conformational coating formulationscommercially available under the “QUICK CURE” trademark from theSpecialty Coating Systems subsidiary of Union Carbide Chemicals &Plastics Technology Corp., Indianapolis, Ind., and sold under theproduct designations B-565, B-566, B-576 and BT-5376; ultraviolet curingadhesive formulations commercially available from Loctite Corp.,Newington, Conn. under the product names UV OPTICALLY CLEAR ADH, MULTIPURPOSE UV ADHESIVE, “IMPRUV” LV PLOTTING COMPOUND and “LOCQUIC”ACTIVATOR 707; ultraviolet curable urethane formulations commerciallyavailable from Norland Products, Inc., New Brunswick, N.J., and soldunder the product designations “NORLAND NOA 61”, “NORLAND NOA 65” and“NORLAND NOA 68”; and ultraviolet curable acrylic formulationscommercially available from Dymax Corp., Torrington, Conn., including“DYMAX LIGHT-WELD 478”.

By employing polyfunctional monomers, like difunctional monomers, orcross-linking agents, cross-linked polychromic solid films may beadvantageously prepared. Such cross-linking tends to improve thephysical properties and characteristics (e.g., mechanic al strength) ofthe resulting polychromic solid films. Cross-linking during cure totransform the electrochromic monomer composition into a polychromicsolid film may be achieved by means of free radical ionic initiation bythe exposure to electromagnetic radiation. This may be accomplished bycombining together all the components of the particular electrochromicmonomer composition and thereafter effecting cure. Alternatively,cross-links may be achieved by exposing to electromagnetic radiation theelectrochromic monomer composition for a time sufficient to effect apartial cure, whereupon further electromagnetic radiation and/or athermal influence may be employed to effect a more complete in situ cureand transformation into the polychromic solid film.

Suitable polyfunctional monomers for use in preparing polychromic filmsshould have at least two reactive functionalities, and may be selectedfrom, among others, ethylene glycol diacrylate, ethylene glycoldimethacrylate, 1,2-butylene dimethacrylate, 1,3-butylenedimethacrylate, 1,4-butylene dimethacrylate, propylene glycoldiacrylate, propylene glycol dimethacrylate, diethylene glycoldiacrylate, dipropylene glycol diacrylate, divinyl benzene, divinyltoluene, diallyl tartrate, allyl maleate, divinyl tartrate, triallylmelamine, glycerine trimethacrylate, diallyl maleate, divinyl ether,diallyl monomethylene glycol citrate, ethylene glycol vinyl allylcitrate, allyl vinyl maleate, diallyl itaconate, ethylene glycol diesterof itaconic acid, polyester of maleic anhydride with triethylene glycol,polyallyl glucoses (e.g., triallyl glucose), polyallyl sucroses (e.g.,pentaallyl sucrose diacrylate), glucose dimethacrylate, pentaerythritoltetraacrylate, sorbitol dimethacrylate, diallyl aconitate, divinylcitrasonate, diallyl fumarate, allyl methacrylate and polyethyleneglycol diacrylate.

Ultraviolet radiation absorbing monomers may also be advantageouslyemployed herein. Preferred among such monomers are1,3-bis-(4-benzoyl-3-hydroxyphenoxy)-2-propylacrylate,2-hydroxy-4-acryloxyethoxybenzophenone, 2-hydroxy-4-octoxybenzophenoneand 4-methacryloxy-2-hydroxybenzophenone, as they perform the dualfunction of acting as a monomer component, or a portion thereof, and asan ultraviolet stabilizing agent.

The density of the cross-link within the resulting polychromic solidfilm tends to increase with the amount and/or the degree offunctionality of polyfunctional monomer present in the electrochromicmonomer composition. Cross-linking density within a polychromic solidfilm may be achieved or further increased by adding to theelectrochromic monomer composition cross-linking agents, whichthemselves are incapable of undergoing further polymerization. Inaddition to increasing the degree of cross-linking within the resultingpolychromic solid film, the use of such cross-linking agents in theelectrochromic monomer composition may enhance the prolonged colorationperformance of the resulting polychromic solid film. Included among suchcross-linking agents are polyfunctional hydroxy compounds, such asglycols and glycerol, polyfunctional primary or secondary aminocompounds and polyfunctional mercapto compounds. Among the preferredcross-linking agents are pentaerythritol,2-ethyl-2-(hydroxymethyl)-1,3-propanediol, the poly(caprolactone) diolshaving molecular weights of 1,250,2,000 and 3,000, and polycarbonatediol available from Polysciences, Inc. and the polyfunctional hydroxycompounds commercially available under the “TONE” tradename from UnionCarbide Chemicals and Plastics Co. Inc., Danbury, Conn., such asÿ-caprolactone triols (known as “TONE” 0301, “TONE” 0305 and “TONE”0310). Among the preferred glycols are the poly(ethylene glycols), likethose sold under the “CARBOWAX” tradename by the Industrial Chemicaldivision of Union Carbide Corp., Danbury, Conn. such as “CARBOWAX” PEG200, PEG 300, PEG 400, PEG 540 Blend, PEG 600, PEG 900, PEG 1000, PEG1450, PEG 3350, PEG 4600, and PEG 8000, with “CARBOWAX” PEG 1450 beingthe most preferred among this group, and those available fromPolysciences, Inc.

Polychromic solid films that perform well under prolonged coloration maybe prepared from electrochromic monomer compositions that contain as amonomer component at least some portion of a polyfunctionalmonomer—e.g., a difunctional monomer.

By preferably using polyfunctional monomers having their functionalgroups spaced apart to such an extent so as to enhance the flexibilityof the resulting polychromic solid film, polychromic solid films may beprepared with a minimum of shrinkage during the transformation processand that also perform well under prolonged coloration.

While it is preferable to have electrochromic monomer compositions whichcontain a monomer component having polyfunctionality in preparingpolychromic solid films that perform well under prolonged coloration,electrochromic monomer compositions that exhibit enhanced resistance toshrinkage when transformed into polychromic solid films preferablycontain certain monofunctional monomers. In this regard, depending onthe specific application, some physical properties and characteristicsof polychromic solid films may be deemed of greater import than others.Thus, superior performance in terms of resistance to shrinkage during insitu curing of the electrochromic monomer composition to the polychromicsolid film may be balanced with the prolonged coloration performance ofthe resulting polychromic solid film to achieve the properties andcharacteristics desirable of that polychromic solid film.

Those of ordinary skill in the art may make appropriate choices amongthe herein described monomers—monofanctional and polyfunctional, such asdifunctional—and cross-linking agents to prepare a polychromic solidfilm having beneficial properties and characteristics for the specificapplication by choosing such combinations of a monofunctional monomer toa polyfunctional monomer or a monofanctional monomer to a cross-linkingagent in an equivalent ratio of about 1:1 or greater.

In the preferred electrochromic monomer compositions, photoinitiators orphotosensitizers may also be added to assist the initiation of the insitu curing process. Such photoinitiators or photosensitizers enhancethe rapidity of the curing process when the electrochromic monomercompositions are exposed to electromagnetic radiation. These materialsinclude, but are not limited to, radical initiation type and cationicinitiation type polymerization initiators such as benzoin derivatives,like the n-butyl, i-butyl and ethyl benzoin alkyl ethers, and thosecommercially available products sold under the “ESACURE” tradename bySartomer Co., such as “ESACURE” TZT (trimethyl benzophenone blend), KB1(benzildimethyl ketal), KB60 (60% solution of benzildimethyl ketal), EB3(mixture of benzoin n-butyl ethers), KIP 100F (ÿ-hydroxy ketone), KT37(TZT and ÿ-hydroxy ketone blend), ITX (i-propylthioxanthone), X15 (ITXand TZT blend), and EDB [ethyl-4-(dimethylamino)-benzoate]; thosecommercially available products sold under the “IRGACURE” and “DAROCURE”tradenames by Ciba Geigy Corp., Hawthorne, N.Y., specifically “IRGACURE”184, 907, 369, 500, 651, 261, 784 and “DAROCURE” 1173 and 4265,respectively; the photoinitiators commercially available from UnionCarbide Chemicals and Plastics Co. Inc., Danbury, Conn., under the“CYRACURE” tradename, such as “CYRACURE” UVI-6974 (mixed triarylsulfonium hexafluoroantimonate salts) and UVI-6990 (mixed triarylsulfonium hexafluorophosphate salts); and the visible light [blue]photoinitiator, dl-camphorquinone.

Of course, when those of ordinary skill in the art choose a commerciallyavailable ultraviolet curable formulation, it may no longer be desirableto include as a component within the electrochromic monomer compositionan additional monomer to that monomer component already present in thecommercial formulation. And, as many of such commercially availableultraviolet curable formulations contain a photoinitiator orphotosensitizer, it may no longer be desirable to include this optionalcomponent in the electrochromic monomer composition. Nevertheless, amonomer, or a photoinitiator or a photosensitizer, may still be added tothe electrochromic monomer composition to achieve beneficial results,and particularly when specific properties and characteristics aredesired of the resulting polychromic solid film.

With an eye toward maintaining the homogeneity of the electrochromicmonomer composition and the polychromic solid film which results afterin situ cure, those of ordinary skill in the art should choose theparticular components dispersed throughout, and their relativequantities, appropriately. One or more compatibilizing agents may beoptionally added to the electrochromic monomer composition so as toaccomplish this goal. Such compatibilizing agents include, among others,combinations of plasticizers recited herein, a monomer component havingpolyfunctionality and cross-linking agents that provide flexiblecross-links. See supra.

Many electrochromic compounds absorb electromagnetic radiation in theabout 290 nm to about 400 nm ultraviolet region. Because solar radiationincludes an ultraviolet region between about 290 nm to about 400 nm, itis often desirable to shield such electrochromic compounds fromultraviolet radiation in that region. By so doing, the longevity andstability of the electrochromic compounds may be improved. Also, it isdesirable that the polychromic solid film itself be stable toelectromagnetic radiation, particularly in that region. This may beaccomplished by adding to the electrochromic monomer composition anultraviolet stabilizing agent (and/or a self-screening plasticizer whichmay act to block or screen such ultraviolet radiation) so as to extendthe functional lifetime of the resulting polychromic solid film. Suchultraviolet stabilizing agents (and/or self-screening plasticizers)should be substantially transparent in the visible region and functionto absorb ultraviolet radiation, quench degradative free radicalreaction formation and prevent degradative oxidative reactions.

As those of ordinary skill in the art will readily appreciate, thepreferred ultraviolet stabilizing agents, which are usually employed ona by-weight basis, should be selected so as to be compatible with theother components of the electrochromic monomer composition, and so thatthe physical, chemical or electrochemical performance of, as well as thetransformation into, the resulting polychromic solid film is notadversely affected.

Although many materials known to absorb ultraviolet radiation may beemployed herein, preferred ultraviolet stabilizing agents include“UVINUL” 400 [2,4-dihydroxybenzophenone (manufactured by BASF Corp.,Wyandotte, Mich.)], “UVINUL” D 49[2,2′-dihydroxy-4,4′-dimethoxybenzophenone (BASF Corp.)], “UVINUL” N 35[ethyl-2-cyano-3,3-diphenylacrylate (BASF Corp.)], “UVINUL” N 539[2-ethylhexyl-2-cyano-3,3′-diphenylacrylate (BASF Corp.)], “UVINUL” M 40[2-hydroxy-4-methoxybenzophenone (BASF Corp.)], “UVINUL” M 408[2-hydroxy-4-octoxybenzophenone (BASF Corp.)], “TINUVIN” P[2-(2′-hydroxy-5′-methylphenyl)-triazole] (Ciba Geigy Corp.)], “TINUVIN”327 [2-(3′,5′-di-t-butyl-2′-hydroxyphenyl)-5-chloro-benzotriazole (CibaGeigy Corp.)], “TINUVIN” 328[2-(3′,5′-di-n-pentyl-2′-hydroxyphenyl)-benzotriazole (Ciba GeigyCorp.)] and “CYASORB UV” 24 [2,2′-dihydroxy-4-methoxy-benzophenone(manufactured by American Cyanamid Co., Wayne, N.J.)], with “UVINUL” M40, “UVINUL M” 408, “UVINUL” N 35 and “UVINUL” N 539 being the mostpreferred ultraviolet stabilizing agents when used in a by-weight rangeof about 0.1% to about 15%, with about 4% to about 10% being preferred.

Since solar radiation includes an ultraviolet region only between about290 nm and 400 nm, the cure wave length of the electrochromic monomercomposition, the peak intensity of the source of electromagneticradiation, and the principle absorbance maxima of the ultravioletstabilizing agents should be selected to provide a rapid and efficienttransformation of the electrochromic monomer compositions into thepolychromic solid films, while optimizing the continued long-termpost-cure stability to outdoor weathering and all-climate exposure ofpolychromic solid films.

An electrolytic material may also be employed in the electrochromicmonomer composition to assist or enhance the conductivity of theelectrical current passing through the resulting polychromic solid film.The electrolytic material may be selected from a host of knownmaterials, preferred of which are tetraethylammonium perchlorate,tetrabutylammonium tetrafluoroborate, tetrabutylammoniumhexafluorophosphate, tetrabutylammonium trifluoromethane sulfonate,lithium salts and combinations thereof, with tetrabutylammoniumhexafluorophosphate and tetraethylammonium perchlorate being the mostpreferred.

In addition, adhesion promoting agents or coupling agents may be used inthe preferred electrochromic monomer compositions to further enhance thedegree to which the resulting polychromic solid films adhere to thecontacting surfaces. Adhesion promoting or coupling agents, whichpromote such enhanced adhesion, include silane coupling agents, andcommercially available adhesion promoting agents like those sold bySartomer Co., such as Alkoxylated Trifunctional Acrylate (9008),Trifunctional Methacrylate Ester (9010 and 9011), Trifunctional AcrylateEster (9012), Aliphatic Monofunctional Ester (9013 and 9015) andAliphatic Difunctional Ester (9014). Moreover, carboxylated vinylmonomers, such as methacrylic acid, vinyl carboxylic acid and the likemay be used to further assist the development of good adhesion to thecontacting surfaces.

And, coloring agents, spacers, anti-oxidizing agents, flame retardingagents, heat stabilizing agents and combinations thereof may be added tothe electrochromic monomer compositions, choosing of course thosematerials in appropriate quantities depending upon the specificapplication of the resulting polychromic solid film. For instance, ablue-tinted electrochromic automotive mirror, such as described herein,may be prepared by dispersing within the electrochromic monomercomposition a suitable ultraviolet stable coloring agent, such as“NEOZAPON” BLUE ™ 807 (a phthalocyanine blue dye, available commerciallyfrom BASF Corp., Parsippany, N.J.) and “NEOPEN” 808 (a phthalocyanineblue dye, available commercially from BASF Corp.).

Polychromic solid films may be prepared within an electrochromic deviceby introducing an electrochromic monomer composition to a film formingmeans, such as the vacuum backfilling technique, which fills a cavity ofan assembly by withdrawing into the cavity the electrochromic monomercomposition while the assembly is in an environment of reducedatmospheric pressure [see e.g., Varaprasad II], the two hole fillingtechnique, where the electrochromic monomer composition is dispensedunder pressure into the assembly through one hole while a gentle vacuumis applied at the other hole [see e.g., Varaprasad III], or with thesandwich lamination technique, which contemporaneously creates and fillsa cavity of an assembly by placing on one or both substrates either athermoplastic sealing means to act as a spacing means [see commonlyassigned U.S. Pat. No. 5,233,461 (Dornan)] or glass beads of nominaldiameter, and then exposing to electromagnetic radiation at least oneclear substrate of the assembly constructed by any of the abovemanufacturing techniques (containing the low viscosity electrochromicmonomer composition) for a time sufficient to transform theelectrochromic monomer composition into a polychromic solid film.

In connection with such film forming means, spacers, such as glassbeads, may be dispensed across the conductive surface of one or bothsubstrates, or dispersed throughout the electrochromic monomercomposition which may then be dispensed onto the conductive surface ofone or both substrates, to assist in preparing a polychromic solid filmwhich contacts, in abutting relationship, the conductive surface of thetwo substrates. Similarly, a pre-established spacing means of solidmaterial, such as tape, pillars, walls, ridges and the like, may also beemployed to assist in determining the interpane distance between thesubstrates in which a polychromic solid film may be prepared to contact,in abutting relationship with, the conductive surface of the twosubstrates.

Polychromic solid films may also be prepared separately from theelectrochromic device, and thereafter placed between, and in abuttingrelationship with, the conductive surface of the two substrates used inconstructing the device. Many known film manufacturing processes may beemployed as a film forming means to manufacture polychromic solid films.Included among these processes are calendering, casting, rolling,dispensing, coating, extrusion and thermoforming. For a non-exhaustivedescription of such processes, see Modern Plastics Encyclopedia 1988,203-300, McGraw-Hill Inc., New York (1988). For instance, theelectrochromic monomer composition may be dispensed or coated onto theconductive surface of a substrate, using conventional techniques, suchas curtain coating, spray coating, dip coating, spin coating, rollercoating, brush coating or transfer coating.

As described above, polychromic solid films may be prepared as aself-supporting solid film which may thereafter be contacted withconductive substrates.

For instance, an electrochromic monomer composition may be continuouslycast or dispensed onto a surface, such as a fluorocarbon surface and thelike, to which the polychromic solid film, transformed therefrom byexposure to electromagnetic radiation, does not adhere. In this way,polychromic solid films may be continuously prepared, and, for example,reeled onto a take-up roller and stored for future use. Thus, when aparticular electrochromic device is desired, an appropriately shapedportion of the stored polychromic solid film may be cut from the rollusing a die, laser, hot wire, blade or other cutting means. This nowcustom-cut portion of polychromic solid film may be contacted with theconductive substrates to form an electrochromic device.

For example, the custom-cut portion of the polychromic solid film may belaminated between the conductive surface of two transparent conductivecoated substrates, such as ITO or tin oxide coated glass substrates, twoITO or tin oxide coated “MYLAR” [polyethylene terephthalate film(commercially available from E.I. du Pont de Nemours and Co.,Wilmington, Del.)] substrates or one ITO or tin oxide coated glasssubstrate and one ITO or tin oxide coated “MYLAR” substrate. To thisend, it may be desirable to allow for residual cure in the storedpolychromic solid film so that adhesion to the conductive substrates inthe laminate to be formed is facilitated and optimized.

In this regard, a polychromic solid film may be prepared by the filmforming means of extrusion or calendaring wherein the electrochromicmonomer composition is transformed into the polychromic solid film byexposure to electromagnetic radiation prior to, contemporaneously with,or, if the electrochromic monomer composition is sufficiently viscous,after passing through the extruder or calendar. Thereafter, thepolychromic solid film may be placed between, and in abuttingrelationship with, the conductive surface of the substrates, and thenconstruction of the electrochromic device may be completed.

While preparing polychromic solid films, the viscosity of theelectrochromic monomer composition may be controlled to optimize itsdispensability by adjusting the temperature of (1) the electrochromicmonomer composition itself, (2) the substrates on which theelectrochromic monomer composition may be placed to assemble theelectrochromic device or (3) the processing equipment used to preparepolychromic solid films (if the polychromic film is to be preparedindependently from the substrates of the electrochromic devices). Forexample, the temperature of the electrochromic monomer composition, thesubstrates or the equipment or combinations thereof may be elevated todecrease the viscosity of the electrochromic monomer composition.Similarly, the uniformity on the substrate of the dispensedelectrochromic monomer composition may be enhanced using laminationtechniques, centrifuge techniques, pressure applied from the atmosphere(such as with vacuum bagging), pressure applied from a weighted object,rollers and the like.

The substrates employed in the electrochromic devices of U.S. patentapplication Ser. No. 08/193,557, filed Feb. 8, 1994 (now abandoned)(“the '557 application”) may be constructed from materials that aresubstantially inflexible as well as flexible depending on theapplication to which they are to be used. In this regard, the substratesmay be constructed from substantially inflexible substrates, such asglass, laminated glass, tempered glass, optical plastics, such aspolycarbonate, acrylic and polystyrene, and flexible substrates, such as“MYLAR” film. Also, the glass substrates suitable for use herein may betinted specialized glass which is known to significantly reduceultraviolet radiation transmission while maintaining high visible lighttransmission. Such glass, often bearing a blue colored tint, provides acommercially acceptable silvery reflection to electrochromic automotivemirrors even when the polychromic solid film is prepared containing anultraviolet stabilizing agent or other component which may have atendency to imbue a yellowish appearance to the polychromic solid film.Preferably, blue tinted specialized glass may be obtained commerciallyfrom Pittsburgh Plate Glass Industries, Pittsburgh, Pa. as “SOLEXTRA”7010; Ford Glass Co., Detroit, Mich. as “SUNGLAS” Blue; or Asahi GlassCo., Tokyo, Japan under the “SUNBLUE” tradename.

Whether the chosen substrate is substantially inflexible or flexible, atransparent conductive coating, such as indium tin oxide (“ITO”) ordoped-tin oxide, is coated on a surface of the substrate making thatsurface suitable for placement in abutting relationship with apolychromic solid film.

The choice of substrate may influence the choice of processingtechniques used to prepare the polychromic solid film or the type ofelectrochromic device assembled. For example, when assembling anelectrochromic device from flexible substrates, an electrochromicmonomer composition may be advantageously applied to such flexiblesubstrates using a roll-to-roll system where the flexible substrates arereleased from rolls (that are aligned and rotate in directions oppositeto one another), and brought toward one another in a spaced-apartrelationship. In this way, the electrochromic monomer composition may bedispensed or injected onto one of the flexible substrates at the pointwhere the two flexible substrates are released from their respectiverolls and brought toward one another, while being contemporaneouslyexposed to electromagnetic radiation for a time sufficient to transformthe electrochromic monomer composition into a polychromic solid film.

The dispensing of the electrochromic monomer composition may be effectedthrough a first injection nozzle positioned over one of the rolls offlexible substrate. A weathering barrier forming material, such as acuring epoxide like an ultraviolet curing epoxide, may be dispensed inan alternating and synchronized manner onto that flexible substratethrough a second injection nozzle positioned adjacent to the firstinjection nozzle. By passing in the path of these nozzles as acontinuously moving ribbon, a flexible substrate may be contacted withthe separate polymerizable compositions in appropriate amounts andpositions on the flexible substrate.

In manufacturing flexible electrochromic assemblies having a dimensionthe full width of the roll of flexible substrate, a weathering barrierforming material may be dispensed from the second injection nozzle whichmay be positioned inboard (typically about 2 mm to about 25 mm) from theleftmost edge of the roll of flexible substrate. The first injectionnozzle, positioned adjacent to the second injection nozzle, may dispensethe electrochromic monomer composition onto most of the full width ofthe roll of flexible substrate. A third injection nozzle, alsodispensing weathering barrier forming material, may be positionedadjacent to, but inboard from, the rightmost edge of that roll offlexible substrate (typically about 2 mm to about 25 mm). In thismanner, and as described above, a continuous ribbon of a flexibleelectrochromic assembly may be formed (upon exposure to electromagneticradiation) which, in turn, may be taken up onto a take-up roller. By sodoing, a flexible electrochromic assembly having the width of the rollof flexible substrate, but of a particular length, may be obtained byunrolling and cutting to length an electrochromic assembly of aparticular size.

Should it be desirable to have multiple flexible electrochromicassemblies positioned in the same taken-up roll, multiple nozzles may beplaced appropriately at positions throughout the width of one of therolls of flexible substrate, and the dispensing process carried outaccordingly.

In that regard, a small gap (e.g., about 5 mm to about 50 mm) should bemaintained where no dispensing occurs during the introduction of theelectrochromic monomer composition and the weathering barrier formingmaterial onto the substrate so that a dead zone is created where neitherthe electrochromic monomer composition nor the weathering barrierforming material is present. Once the weathering barrier and polychromicsolid film have formed (see infra), the electrochromic assembly may beisolated by cutting along the newly created dead zones of the flexibleassemblies. This zone serves conveniently as a cutting area to formelectrochromic assemblies of desired sizes.

And, the zones outboard of the respective weathering barriers serve asconvenient edges for attachment of a means for introducing an appliedpotential to the flexible electrochromic assemblies, such as bus bars.Similarly, the bisection of the dead zones establishes a convenientposition onto which the bus bars may be affixed.

While each of the weathering barrier forming material and theelectrochromic monomer composition may be transformed into a weatheringbarrier and a polychromic solid film, respectively, by exposure toelectromagnetic radiation, the required exposures to complete therespective transformations may be independent from one another. Theweathering barrier forming material may also be thermally cured to formthe weathering barrier.

The choice of a particular electromagnetic radiation region to effect insitu cure may depend on the particular electrochromic monomercomposition to be cured. In this regard, typical sources ofelectromagnetic radiation, such as ultraviolet radiation, include:mercury vapor lamps; xenon arc lamps; “H”, “D”, “X”, “M”, “V” and “A”fusion lamps (such as those commercially available from Fusion UV CuringSystems, Buffalo Grove, Ill.); microwave generated ultravioletradiation; solar power and fluorescent light sources. Any of theseelectromagnetic radiation sources may use in conjunction therewithreflectors and filters, so as to focus the emitted radiation within aparticular electromagnetic region. Similarly, the electromagneticradiation may be generated directly in a steady fashion or in anintermittent fashion so as to minimize the degree of heat build-up.Although the region of electromagnetic radiation employed to in situcure the electrochromic monomer compositions into polychromic solidfilms is often referred to herein as being in the ultraviolet region,that is not to say that other regions of radiation within theelectromagnetic spectrum may not also be suitable. For instance, incertain situations, visible radiation may also be advantageouslyemployed.

Bearing in mind that some or all of the components of the electrochromicmonomer composition may inhibit, retard or suppress the in situ curingprocess, a given source of electromagnetic radiation should have asufficient intensity to overcome the inhibitive effects of thosecomponents so as to enable to proceed successfully the transformation ofthe electrochromic monomer composition into the polychromic solid film.By choosing a lamp with a reflector and, optionally, a filter, a sourcewhich itself produces a less advantageous intensity of electromagneticradiation may suffice. In any event, the chosen lamp preferably has apower rating of at least about 100 watts per inch (about 40 watts percm), with a power rating of at least about 300 watts per inch (about 120watts per cm) being particularly preferred. Most preferably, thewavelength of the lamp and its output intensity should be chosen toaccommodate the presence of ultraviolet stabilizing agents incorporatedinto electrochromic monomer compositions. Also, a photoinitiator orphotosensitizer, if used, may increase the rate of in situ curing orshift the wavelength within the electromagnetic radiation spectrum atwhich in situ curing will occur in the transformation process.

During the in situ curing process, the electrochromic monomercomposition will be exposed to a source of electromagnetic radiationthat emits an amount of energy, measured in KJ/m², determined byparameters including: the size, type and geometry of the source; theduration of the exposure to electromagnetic radiation; the intensity ofthe radiation (and that portion of radiation emitted within the regionappropriate to effect curing); the absorbance of electromagneticradiation by any intervening materials, such as substrates, conductivecoatings and the like; and the distance the electrochromic monomercomposition lies from the source of radiation. Those of ordinary skillin the art will readily appreciate that the polychromic solid filmtransformation may be optimized by choosing appropriate values for theseparameters in view of the particular electrochromic monomer composition.

The source of electromagnetic radiation may remain stationary while theelectrochromic monomer composition passes through its path.Alternatively, the electrochromic monomer composition may remainstationary while the source of electromagnetic radiation passesthereover or therearound to complete the transformation into apolychromic solid film. Still alternatively, both may traverse oneanother, or for that matter remain stationary, provided that theelectrochromic monomer composition is exposed to the electrochromicradiation for a time sufficient to effect such in situ curing.

Commercially available curing systems, such as the Fusion UV CuringSystems F-300 B [Fusion UV Curing Systems, Buffalo Grove, Ill.], HanoviaUV Curing System [Hanovia Corp., Newark, N.J. ] and RC-500 A Pulsed UVCuring System [Xenon Corp., Woburn, Mass.], are well-suited toaccomplish the transformation. Also, a Sunlighter UV chamber fitted withlow intensity mercury vapor lamps and a turntable may accomplish thetransformation.

The required amount of energy may be delivered by exposing theelectrochromic monomer composition to a less powerful source ofelectromagnetic radiation for a longer period of time, through forexample multiple passes, or conversely, by exposing it to a morepowerful source of electromagnetic radiation for a shorter period oftime. In addition, each of those multiple passes may occur with a sourceat different energy intensities. In any event, those of ordinary skillin the art should choose an appropriate source of electromagneticradiation depending on the particular electrochromic monomercomposition, and place that source at a suitable distance therefromwhich, together with the length of exposure, optimizes thetransformation process. Generally, a slower, controlled cure, such asthat achieved by multiple passes using a less intense energy source, maybe preferable over a rapid cure using a more intense energy source, forexample, to minimize shrinkage during the transformation process. Also,it is desirable to use a source of electromagnetic radiation that isdelivered in an intermittent fashion, such as by pulsing or strobing, soas to ensure a thorough and complete cure without causing excessive heatbuild-up.

In transforming electrochromic monomer compositions into polychromicsolid films, shrinkage may be observed during and after thetransformation process of the electrochromic monomer composition into apolychromic solid film. This undesirable event may be controlled orlessened to a large extent by making appropriate choices among thecomponents of the electrochromic monomer composition. For instance,appropriately chosen polyfunctional monomers or cross-linking agents mayenhance resistance to shrinkage during the transformation process. Inaddition, a conscious control of the type and amount of plasticizer usedin the electrochromic monomer composition may also tend to enhanceresistance to shrinkage. While shrinkage may also be observed withpolychromic solid films that have been subjected to environmentalconditions, especially conditions of environmental accelerated aging,such as thermal cycling and low temperature soak, a conscious choice ofcomponents used in the electrochromic monomer composition may tend tominimize this event as well. In general, shrinkage may be decreased asthe molecular weight of the monomer employed is increased, and by usingindex matched inert fillers, such as glass beads or fibres.

Electrochromic devices may be manufactured with polychromic solid filmsof a particular thickness by preparing partially-cured polychromic solidfilms between the glass substrates of electrochromic assemblies withspacers or a thermoplastic spacing means having been placed on one orboth of the substrates. This partially-cured polychromic solid filmshould have a thickness slightly greater than that which the resultingpolychromic solid film will desirably assume in the completed device.The electrochromic assemblies should then be subjected to compression,such as that provided by an autoclave/vacuum bagging process, andthereafter be exposed to electromagnetic radiation to complete thetransformation into a polychromic solid film with the desired filmthickness.

FIGS. 18 and 19 show an electrochromic device assembled from thepolychromic solid films of U.S. patent application Ser. No. 08/193,557,filed Feb. 8, 1994 (now abandoned) (“the '557 application”). Theelectrochromic assembly 1′″ includes two substantially planar substrates2″′, 3″′ positioned substantially parallel to one another. It ispreferable that these substrates 2′″, 3′″ be positioned as close toparallel to one another as possible so as to avoid double imaging, whichis particularly noticeable in mirrors, especially when theelectrochromic media—i.e., the polychromic solid film—is colored to adimmed state.

A source of an applied potential need be introduced to theelectrochromic assembly 1′″ so that polychromic solid film 6′″ may colorin a rapid, intense and uniform manner. That source may be connected byelectrical leads 8′″ to conducting strips, such as bus bars 7′″. The busbars 7′″ may be constructed of a metal, such as copper, stainless steel,aluminum or solder, or of conductive frits and epoxides, and should beaffixed to a conductive coating 4′″, coated on a surface of each of thesubstrates 2′″, 3′″. An exposed portion of the conductive coating 4′″should be provided for the bus bars 7′″ to adhere by the displacement ofthe coated substrates 2′″, 3′″ in opposite directions relative to eachother—lateral from, but parallel to—, with polychromic solid film 6′″positioned between, and in abutting relationship with, the conductivesurface of the two substrates.

As noted above, coated on a surface of each of these substrates 2′″, 3′″is a substantially transparent conductive coating 4′″. The conductivecoating 4′″ is generally from about 300 Å to about 10,000 Å inthickness, having a refractive index in the range of about 1.6 to about2.2. Preferably, a conductive coating 4′″ with a thickness of about1,200 Å to about 2,300 Å, having a refractive index of about 1.7 toabout 1.9, is chosen depending on the desired appearance of thesubstrate when the polychromic solid film situated therebetween iscolored.

The conductive coating 4′″ should also be highly and uniformlyconductive in each direction to provide a substantially uniform responseas to film coloring once a potential is applied. The sheet resistance ofthese transparent conductive substrates 2′″, 3′″ may be below about 100ohms per square, with about 6 ohms per square to about 20 ohms persquare being preferred. Such substrates 2′″, 3′″ may be selected fromamong those commercially available as glass substrates, coated withindium tin oxide (“ITO”) from Donnelly Corporation, Holland, Mich., ortin oxide-coated glass substrates sold by the LOF Glass division ofLibbey-Owens-Ford Co., Toledo, Ohio under the tradename of “TEC-Glass”products, such as “TEC 10” (10 ohms per square sheet resistance), “TEC12” (12 ohms per square sheet resistance) and “TEC 20” (20 ohms persquare sheet resistance) tin oxide-coated glass. Moreover, tin oxidecoated glass substrates, commercially available from Pittsburgh PlateGlass Industries, Pittsburgh, Pa. under the “SUNGATE” tradename, may beadvantageously employed herein. Also, substantially transparentconductive coated flexible substrates, such as ITO deposited ontosubstantially clear or tinted “MYLAR”, may be used. Such flexiblesubstrates are commercially available from Southwall Corp., Palo Alto,Calif.

The conductive coating 4′″ coated on each of the substrates 2′″, 3′″ maybe constructed from the same material or different materials, includingtin oxide, ITO, ITO-FW, ITO-HW, ITO-HWG, doped tin oxide, such asantimony-doped tin oxide and fluorine-doped tin oxide, doped zinc oxide,such as antimony-doped zinc oxide and aluminum-doped zinc oxide, withITO being preferred.

The substantially transparent conductive coated substrates 2′″, 3′″ maybe of the full-wave length-type (“FW”) (about 6 ohms per square to about8 ohms per square sheet resistance), the half-wave length-type (“HW”)(about 12 ohms per square to about 15 ohms per square sheet resistance)or the half-wave length green-type (“HWG”) (about 12 ohms per square toabout 15 ohms per square sheet resistance). The thickness of FW is about3,000 Å in thickness, HW is about 1,500 Å in thickness and HWG is about1,960 Å in thickness, bearing in mind that these substantiallytransparent conductive coated substrates 2′″, 3′″ may vary as much asabout 100 to about 200 Å. HWG has a refractive index of about 1.7 toabout 1.8, and has an optical thickness of about five-eighths wave toabout two-thirds wave. HWG is generally chosen for electrochromicdevices, especially reflective devices, such as mirrors, whose desiredappearance has a greenish hue in color when a potential is applied.

Optionally, and for some applications desireably, the spaced-apartsubstantially transparent conductive coated substrates 2′″, 3′″ may havea weather barrier 5′″ placed therebetween or therearound. The use of aweather barrier 5′″ in the electrochromic devices of U.S. patentapplication Ser. No. 08/193,557, filed Feb. 8, 1994 (now abandoned)(“the '557 application”) is for the purpose of preventing environmentalcontaminants from entering the device during long-term use under harshenvironmental conditions rather than to prevent escape of electrochromicmedia, such as with an electrochemichromic device. Weather barrier 5′″may be made from many known materials, with epoxy resins coupled withspacers, plasticized polyvinyl butyral (available commercially under the“SAFLEX” tradename from Monsanto Co., St. Louis, Mo.), ionomer resins(available commercially under the “SURLYN” tradename from E.I. du Pontde Nemours and Co., Wilmington, Del.) and “KAPTON” high temperaturepolyamide tape (available commercially from E.I. du Pont de Nemours andCo., Wilmington, Del.) being preferred. In general, it may be desirableto use within the electrochromic device, and particularly for weatherbarrier 5′″, materials such as nitrile containing polymers and butylrubbers that form a good barrier against oxygen permeation fromenvironmental exposure.

In the sandwich lamination technique, see supra, it is the thickness ofthe polychromic solid film itself, especially when a highly viscouselectrochromic monomer composition is used, optionally coupled witheither spacers or a thermoplastic spacing means, assembled within theelectrochromic devices of U.S. patent application Ser. No. 08/193,557,filed Feb. 8, 1994 (now abandoned) (“the '557 application”) thatdetermines the interpane distance of the spaced-apart relationship atwhich the substrates are positioned. This interpane distance may beinfluenced by the addition of spacers to the electrochromic monomercomposition, which spacers, when added to an electrochromic monomercomposition, assist in defining the film thickness of the resultingpolychromic solid film. And, the thickness of the polychromic solid filmmay be about 10 μm to about 1000 μm, with about 20 μm to about 200 μmbeing preferred, a film thickness of about 37 μm to about 74 μm beingparticularly preferred, and a film thickness of about 53 μm being mostpreferred depending of course on the chosen electrochromic monomercomposition and the intended application.

By taking appropriate measures, electrochromic devices manufactured withpolychromic solid films may operate so that, upon application of apotential thereto, only selected portions of the device—i.e., throughthe polychromic solid film—will color in preference to the remainingportions of the device. In such segmented electrochromic devices, linesmay be scored or etched onto the conductive surface of either one orboth of substrates 2′″, 3′″, in linear alignment so as to cause a breakin electrical continuity between regions immediately adjacent to thebreak, by means such as chemical etching, mechanical scribing, laseretching, sand blasting and other equivalent means. By so doing, anaddressable pixel may be created by the break of electrical continuitywhen a potential is applied to a pre-determined portion of theelectrochromic device. The electrochromic device colors in only thatpre-determined portion demonstrating utility, for example, as anelectrochromic mirror, where only a selected portion of the mirroradvantageously colors to assist in reducing locally reflected glare oras an electrochromic information display device.

To prepare an electrochromic device containing a polychromic solid film,the electrochromic monomer composition may be dispensed onto theconductive surface of one of the substrates 2′″ or 3′″. The conductivesurface of the other substrate may then be placed thereover so that theelectrochromic monomer composition is dispersed uniformly onto andbetween the conductive surface of substrates 2′″, 3′″.

This assembly may then be exposed, either in a continuous orintermittent manner, to electromagnetic radiation, such as ultravioletradiation in the region between about 200 nm to about 400 nm for aperiod of about 2 seconds to about 10 seconds, so that theelectrochromic monomer composition is transformed by in situ curing intopolychromic solid film 6′″. The intermittent manner may include multipleexposures to such energy.

Once the electrochromic device is assembled with polychromic solid film6′″, a potential may be applied to the bus bars 7′″ in order to inducefilm coloring. The applied potential may be supplied from a variety ofsources including, but not limited to, any source of alternating current(“AC”) or direct current (“DC”) known in the art, provided that, if anAC source is chosen, control elements, such as diodes, should be placedbetween the source and each of the conductive coatings 4′″ to ensurethat the potential difference between the conductive coatings 4′″ doesnot change polarity with variations in polarity of the applied potentialfrom the source. Suitable DC sources are storage batteries, solarthermal cells, photovoltaic cells or photoelectrochemical cells.

An electrochromic device, such as an electrochromic shade band where agradient opacity panel may be constructed by positioning the bus bars7′″ along the edges of the substrates in such a way so that only aportion—e.g., the same portion—of each of the substrates 2′″, 3′″ havethe bus bars 7′″ affixed thereto. Thus, where the bus bars 7′″ arealigned with one another on opposite substrates 2′″, 3′″, theintroduction of an applied potential to the electrochromic device willcause intense color to be observed in only that region of the deviceonto which an electric field has been created—i.e., only that region ofthe device having the bus bars 7′″ so aligned. A portion of theremaining bleached region will also exhibit color extending from theintensely colored region at the bus bar/non-bus bar transition graduallydissipating into the remaining bleached region of the device.

The applied potential generated from any of these sources may beintroduced to the polychromic solid film of the electrochromic device inthe range of about 0.001 volts to about 5.0 volts. Typically, however, apotential of about 0.2 volts to about 2.0 volts is preferred, with about1 volt to about 1.5 volts particularly preferred, to permit the currentto flow across and color the polychromic solid film 6′″ so as to lessenthe amount of light transmitted therethrough. The extent ofcoloring—i.e., high transmittance, low transmittance and intermediatetransmittance levels—at steady state in a particular device will oftendepend on the potential difference between the conductive surface of thesubstrates 2′″, 3′″, which relationship permits the electrochromicdevices of U.S. patent application Ser. No. 08/193,557, filed Feb. 8,1994 (now abandoned) (“the '557 application”) to be used as “gray-scale”devices, as that term is used by those of ordinary skill in the art.

A zero potential or a potential of negative polarity (i.e., a bleachingpotential) may be applied to the bus bars 7′″ in order to induce highlight transmittance through polychromic solid film 6′″. A zero potentialto about −0.2 volts will typically provide an acceptable response timefor bleaching; nevertheless, increasing the magnitude of the negativepotential to about −0.7 volts will often enhance response times. And, afurther increase in the magnitude of that potential to about −0.8 voltsto about −0.9 volts, or a magnitude of even more negative polarity asthe art-skilled should readily appreciate, may permit polychromic solidfilm 6′″ to form a light-colored tint while colored to a partial- orfully-dimmed state.

In electrochromic devices where the polychromic solid film is formedwithin the assembly by exposure to electromagnetic radiation, theperformance of the device may be enhanced by applying the positivepolarity of the potential to the substrate that faced theelectromagnetic radiation during the transformation process. Thus, inthe case of electrochromic mirrors manufactured in such a manner, thepositive polarity of the potential should be applied to the conductivesurface of the clear, front glass substrate, and the negative polarityof the potential applied to the conductive surface of the silvered, rearglass substrate, to observe such a beneficial effect.

In the context of an electrochromic mirror assembly, a reflectivecoating, having a thickness in the range of 250 Åto about 2,000 Å,preferably about 1,000 Å, should thereafter be applied to one of thetransparent conductive coated glass substrates 2′″ or 3′″ in order toform a mirror. Suitable materials for this layer are aluminum,palladium, platinum, titanium, gold, chromium, silver and stainlesssteel, with silver being preferred. As an alternative to such metalreflectors, multi-coated thin film stacks of dielectric materials or ahigh index single dielectric thin film coating may be used as areflector. Alternatively, one of the conductive coatings 4′″ may be ametallic reflective layer which serves not only as an electrode, butalso as a mirror.

It is clear from the teaching herein that should a window, sun roof orthe like be desirably constructed, the reflective coating need only beomitted from the assembly so that the light which is transmitted throughthe transparent panel is not further assisted in reflecting backtherethrough.

Similarly, an electrochromic optically attenuating contrast filter maybe manufactured in the manner described above, optionally incorporatinginto the electrochromic assembly an anti-reflective means, such as acoating, on the front surface of the outermost substrate as viewed by anobserver (see e.g., Lynam V); an anti-static means, such as a conductivecoating, particularly a transparent conductive coating of ITO, tin oxideand the like; index matching means to reduce internal and interfacialreflections, such as thin films of an appropriately selected opticalpath length; and/or light absorbing glass, such as glass tinted to aneutral density, such as “GRAYLITE” gray tinted glass (commerciallyavailable from Pittsburgh Plate Glass Industries, Pittsburgh, Pa.) and“SUNGLAS” Gray gray tinted glass (commercially available from Ford GlassCo., Detroit, Mich.), to augment contrast enhancement. Moreover, polymerinterlayers, which may be tinted gray, such as those used inelectrochromic constructions as described in Lynam III, may beincorporated into such electrochromic optically attenuating contrastfilters.

Electrochromic optical attenuating contrast filters may be an integralpart of a device or may be affixed to an already constructed device,such as cathode ray tube monitors. For instance, an optical attenuatingcontrast filter may be manufactured from a polychromic solid film andthen affixed, using a suitable optical adhesive, to a device that shouldbenefit from the properties and characteristics exhibited by thepolychromic solid film. Such optical adhesives maximize optical qualityand optical matching, and minimize interfacial reflection, and includeplasticized polyvinyl butyral, various silicones, polyurethanes such as“NORLAND NOA 65” and “NORLAND NOA 68”, and acrylics such as “DYMAXLIGHT-WELD 478”. In such contrast filters, the electrochromic compoundsare chosen for use in the polychromic solid film so that theelectrochromic assembly may color to a suitable level upon theintroduction of an applied potential thereto, and no undesirablespectral bias is exhibited. Preferably, the polychromic solid filmshould dim through a substantially neutral colored partial transmissionstate to a substantially neutral colored full transmission state.

Polychromic solid films may be used in electrochromic devices,particularly glazings and mirrors, whose functional surface issubstantially planar or flat, or that are curved with a convexcurvature, a compound curvature, a multi-radius curvature, a sphericalcurvature, an aspheric curvature, or combinations of such curvature. Forexample, flat electrochromic automotive mirrors may be manufacturedusing the polychromic solid films of U.S. patent application Ser. No.08/193,557, filed Feb. 8, 1994 (now abandoned) (“the '557 application”).Also, convex electrochromic automotive mirrors may be manufactured, withradii of curvature typically in the range of about 25″ to about 250″,preferably in the range of about 35″ to about 100″, as areconventionally known. In addition, multi-radius automotive mirrors, suchas those described in U.S. Pat. No. 4,449,786 (McCord), may bemanufactured using the polychromic solid films of U.S. patentapplication Ser. No. 08/193,557, filed Feb. 8, 1994 (now abandoned)(“the '557 application”). Multi-radius automotive mirrors may be usedtypically on the driver-side exterior of an automobile to extend thedriver's field of view and to enable the driver to safely see rearwardand to avoid blind-spots in the rearward field of view. Generally, suchmirrors comprise a higher radius (even flat) region closer to the driverand a lower radius (i.e., more curved) region outboard from the driverthat serves principally as the blind-spot detection zone in the mirror.Indeed, such polychromic solid film-containing electrochromicmulti-radius automotive mirrors may benefit from the prolongedcoloration performance of polychromic solid films and/or from theability to address individual segments in such mirrors.

Often, a demarcation means, such as a silk-screened or otherwise appliedline of black epoxy, may be used to separate the more curved, outboardblind-spot region from the less curved, inboard region of such mirrors.The demarcation means may also include an etching of a deletion line oran otherwise established break in the electrical continuity of thetransparent conductors used in such mirrors so that either one or bothregions may be individually or mutually addressed. Optionally, thisdeletion line may itself be colored black. Thus, the outboard, morecurved region may operate independently from the inboard, less curvedregion to provide an electrochromic mirror that operates in a segmentedarrangement. Upon the introduction of an applied potential, either ofsuch regions may color to a dimmed intermediate reflectance level,independent of the other region, or, if desired, both regions mayoperate together in tandem.

An insulating demarcation means, such as demarcation lines, dots and/orspots, may be placed within electrochromic devices, such as mirrors,glazings, optically attenuating contrast filters and the like, to assistin creating the interpane distance of the device and to enhance overallperformance, in particular the uniformity of coloration across largearea devices. Such insulating demarcation means, constructed from, forexample, epoxy coupled with glass spacer beads, plastic tape or die cutfrom plastic tape, may be placed onto the conductive surface of one ormore substrates by silk-screening or other suitable technique prior toassembling the device. The insulating demarcation means may begeometrically positioned across the panel, such as in a series ofparallel, uniformly spaced-apart lines, and may be clear, opaque, tintedor colorless and appropriate combinations thereof, so as to appeal tothe automotive stylist.

If the interpane distance between the substrates is to be, for example,about 250 μm, then the insulating demarcation means (being substantiallynon-deformable) may be screened, contacted or adhered to the conductivesurface of a substrate at a lesser thickness, for example, about 150 μmto about 225 μm. Of course, if substantially deformable materials areused as such demarcation means, a greater thickness, for example, about275 μm to about 325 μm, may be appropriate as well. Alternatively, theinsulating demarcation means may have a thickness about equal to that ofthe interpane distance of the device, and actually assist in bondingtogether the two substrates of the device.

In any event, the insulating demarcation means should prevent theconductive surfaces of the two substrates (facing one another in theassembled device) from contacting locally one another to avoidshort-circuiting the electrochromic system. Similarly, should theelectrochromic device be touched, pushed, impacted and the like at someposition, the insulating demarcation means, present within the interpanedistance between the substrates, should prevent one of the conductivesurfaces from touching, and thereby short-circuiting, the otherconductive surface. This may be particularly advantageous when flexiblesubstrates, such as ITO-coated “MYLAR”, are used in the electrochromicdevice.

Although spacers may be added to the electrochromic monomer compositionand/or distributed across the conductive surface of one of thesubstrates prior to assembling the device, such random distributionprovides a degree of uncertainty as to their ultimate location withinthe electrochromic device. By using such a screen-on technique asdescribed above, a more defined and predictable layout of the insulatingdemarcation means may be achieved.

Using such insulating demarcation means, one or both of the substrates,either prior to or after assembly in the device, may be divided intoseparate regions with openings or voids within the insulatingdemarcation means interconnecting adjacent regions so as to permit aready introduction of the electrochromic monomer composition into theassembly.

A demarcation means may be used that is conductive as well, providedthat it is of a smaller thickness than the interpane distance and/or alayer of an insulating material, such as a non-conductive epoxy,urethane or acrylic, is applied thereover so as to prevent conductivesurfaces from contacting one another and thus short-circuiting theelectrochromic assembly. Such conductive demarcation means includeconductive frits, such as silver frits like the # 7713 silver conductivefrit available commercially from E.I. de Pont de Nemours and Co.,Wilmington, Del., conductive paint or ink and/or metal films, such asthose disclosed in Lynam IV. Use of a conductive demarcation means, suchas a line of the # 7713 silver conductive frit, having a width of about0.09375″ and a thickness of about 50 μm, placed on the conductivesurface of one of the substrates of the electrochromic device mayprovide the added benefit of enhancing electrochromic performance byreducing bus bar-to-bus bar overall resistance and thus enhancinguniformity of coloration, as well as rapidity of response, particularlyover large area devices.

In view of the above description of the instant invention, it is evidentthat a wide range of practical opportunities is provided by the teachingherein. The following examples illustrate the benefits and utility ofthe present invention and are provided only for purposes ofillustration, and are not to be construed so as to limit in any way theteaching herein.

Other components may also be added to the electrolyte, with suchcomponents preferably being in solution in liquid-phase electrolytes.These components may include, but are not limited to, ultravioletstabilizing agents, infrared radiation reducing agents, color tintingagents (e.g., dyes or colorants) and combinations thereof. Suitableultraviolet stabilizing agents and color tinting agents are recited inLynam III, the disclosure of which is hereby incorporated herein byreference. For example, a blue-colored dye of the phthalocyanine-type,such as “NEOPEN” 808 (commercially available from BASF Corp.,Parsippany, N.J.), may be added to the electrolyte as a color tintingagent.

Because many redox reaction promoters show a substantial absorbance inthe ultraviolet region of the electromagnetic spectrum from about 250 nmto about 350 nm and the electrochromic solid film itself may bedeleteriously affected by exposure to ultraviolet radiation, it is oftendesirable to shield the redox reaction promoters and electrochromicsolid film from ultraviolet radiation. Thus, by introducing anultraviolet stabilizing agent to the electrolyte, or using a solventwhich itself acts to absorb ultraviolet radiation, the lifetime of theelectrochromic device may be extended. It may be particularlyadvantageous to include ultraviolet stabilizing agents in theelectrolyte for electrochromic mirrors and electrochromic devices whoseintended use may result in exposure to outdoor weathering conditions,such as that encountered by the exterior of a motor vehicle.

Although many materials known to absorb ultraviolet radiation may beemployed herein, preferred ultraviolet stabilizing agents include“UVINUL” 400 [2,4-dihydroxybenzophenone (manufactured by BASF Corp.,Wyandotte, Mich.)], “UVINUL” D 49[2,2′-dihydroxy-4,4′-dimethoxybenzophenone (BASF Corp.)], “UVINUL” N 35[ethyl-2-cyano-3,3-diphenylacrylate (BASF Corp.)], “UVINUL” N 539[2-ethyl hexyl-2-cyano-3,3′-diphenylacrylate (BASF Corp.)], “UVINUL” M40 (2-hydroxy-4-methoxybenzophenone (BASF Corp.)], “UVINUL” M 408[2-hydroxy-4-octoxy-benzophenone (BASF Corp.)], “TINUVIN” P[2-(2H-benzotriazole-2-yl)-4-methylphenyl (manufactured by Ciba GeigyCorp., Hawthorne, N.Y.)], “TINUVIN”327[(2-(3′,5′-di-t-butyl-2′-hydroxyphenyl)-5-chloro-benzotriazole (CibaGeigy Corp.)], “TINUVIN” 328[2-(3′,5′-di-n-pentyl-2′-hydroxyphenyl)-benzotriazole (Ciba GeigyCorp.)], “CYASORB” UV 24 (2,2′-dihydroxy-4-methoxy-benzophenone(manufactured by American Cyanamid Co., Wayne, N.J.)] and combinationsthereof, where a suitable range of the ultraviolet stabilizing agents isfrom about 0.2% (w/v) to about 40% (w/v), with about 5% (w/v) to about15% (w/v) being preferred. The ultraviolet stabilizing agent should bechosen with an eye toward avoiding an adverse affect on performance andelectrolyte function.

In addition, ultraviolet absorbing interlayers may be coated onto, oradhered to, the first substrate and/or second substrate, particularlythe first substrate, to assist in shielding the electrochromic elementfrom the degradative effect of ultraviolet radiation. Suitableultraviolet absorbing interlayers include those recited in Lynam III.

Moreover, to assist in extending the lifetime of the electrochromicdevice, the electrochromic solid film may be placed onto the inwardsurface of the second substrate—i.e., coated onto either the reflectiveelement or the substantially transparent conductive electrode coatingdepending on the particular construction. Location of the electrochromicsolid film on the inward surface of the second substrate may bedesirable where an electrochromic rearview mirror suitable for use onthe exterior of a motor vehicle is intended to be exposed to outdoorweathering, including exposure to ultraviolet radiation.

It may also be desirable to employ ultraviolet absorbing glass orlaminates thereof for the first substrate or for the second substrate inan electrochromic mirror, particularly for the first substrate, or forthe first substrate and/or the second substrate in an electrochromicdevice. Suitable ultraviolet absorbing glass include that which isrecited in Lynam IV. In addition, it may be desirable to employ tinoxide, doped tin oxide, zinc oxide or doped zinc oxide as asubstantially transparent conductive electrode coating on the inwardsurface of the first substrate, ultraviolet stabilizing agents in theelectrolyte, ultraviolet absorbing interlayers, ultraviolet absorbingglass and combinations thereof in conjunction with positioning theelectrochromic solid film on the inward surface of the second substrate.Such constructions, particularly with additional ultraviolet stabilizingagents included in the electrolyte as described supra, facilitatescreening and/or absorption of ultraviolet radiation by the componentsused in the electrochromic mirror or electrochromic device, includingthe first substrate, the conductive electrode coating thereon, and theelectrolyte and its components that are positioned effectively in frontof the potentially ultraviolet sensitive electrochromic solid film.

Addition of ultraviolet stabilizing agents may be particularlyadvantageous when the electrochromic solid film 7 is coated ontoconductive electrode 4′ on the inward surface of substrate 3. (See FIG.5.) In this construction, the ultraviolet stabilizing agents may act toscreen and/or absorb incident ultraviolet radiation before it reachesthe electrochromic solid film 7. By so doing, the chance of irradiatingthe potentially photochromic or otherwise ultraviolet radiationvulnerable electrochromic solid film 7 may be reduced or evensubstantially eliminated. In contrast, when coated onto substantiallytransparent conductive electrode 4 on the inward surface of substrate 2(see FIG. 4), the electrochromic solid film 7 may be directly irradiatedby any incident ultraviolet light that passes through substrate 2. Theultraviolet screening and/or absorbing affect of the electrolyte, whichin this construction is now positioned behind the electrochromic solidfilm 7, has less of an opportunity to shield the electrochromic solidfilm 7 from incident ultraviolet light (although the electrolyte mayeffectively absorb any ultraviolet light which is reflected from thereflective element on substrate 3).

Those of ordinary skill in the art may make appropriate choices amongthe various materials available as described herein for the substrates,coatings, electrochromic solid films and electrolyte components—e.g.,redox reaction promoters, sources of alkali ions and/or protons,solvents, and other components—to prepare electrochromic mirrors andelectrochromic devices capable of generating a substantiallynon-spectral selective gray color suitable for the desired application.In addition, while glass is a suitable choice of material from which thesubstrates may be constructed, other materials may be used, such asoptical plastics like acrylic, polycarbonate, polystyrene and allyldiglycol carbonate (commercially available from Pittsburgh Plastic GlassIndustries, Pittsburgh, Pa. under the tradename “CR-39”).

Reference to the figures will now be made in order to more faithfullydescribe the electrochromic devices, particularly the electrochromicmirrors, of the present invention.

With reference to FIGS. 3A, 3B and 4, it may be seen that theelectrochromic element 1 includes a front substrate 2 and a rearsubstrate 3, each of which is typically glass. However, as described indetail hereinafter, in certain mirror constructions only the front orfirst substrate 2 needs to be at least substantially transparent, and inthose constructions the rear or second substrate 3 need not betransparent at all. (See FIG. 5.) In fact, substrate 3 may be a polishedmetal plate, a metal-coated glass substrate or a conductive ceramicmaterial.

By convention, the first substrate 2 (the frontmost or outermostsubstrate) is the substrate of the electrochromic device positionedclosest to any principal source of incoming or incident electromagneticradiation and, in an electrochromic mirror, the second substrate 3 isthe substrate onto which a layer of reflective material 8 is coated. Putanother way, the first substrate 2 is the substrate into which a driverof or passenger in a motor vehicle may first look through to view animage. In an electrochromic device, such as a glazing, a window or a sunroof for a motor vehicle, the first substrate 2 is the substrate exposeddirectly to, and often in contact with, the outdoor environment and isexposed directly to solar ultraviolet radiation.

Substrates 2, 3 should be positioned substantially parallel to oneanother if planar (or positioned substantially tangentially parallel toone another if bent), or as close to parallel (or tangentially parallel)to one another as possible so as to minimize image separation which maylead to double imaging. Double imaging is particularly noticeable whenmirrors are colored to a dimmed state. Double imaging may be furtherminimized in mirror constructions as described hereinafter.

Onto each of the inward surfaces of substrates 2, 3 is coated aconductive electrode coating 4 or 4′. The conductive electrode coatings4, 4′ may be constructed from the same material or different materials,including transparent electronic conductors, such as tin oxide; indiumtin oxide (“ITO”); half-wave indium tin oxide (“HW-ITO”); full-waveindium tin oxide (“FW-ITO”); doped tin oxides, such as antimony-dopedtin oxide and fluorine-doped tin oxide; doped zinc oxides, such asantimony-doped zinc oxide and aluminum-doped zinc-oxide, with tin oxide,doped tin oxide, zinc oxide or doped zinc oxide being preferred wherelong-term ultraviolet resilience is desired in the device.

In certain mirror constructions, the conductive electrode coating 4′need not be substantially transparent. Rather, the layer of reflectivematerial that serves as the reflective element of the mirror (with anyother coatings used to form a thin film stack) may also serve asconductive electrode coating 4′, thereby allowing a potential to beapplied to the electrochromic element 1. Suitable materials for thislayer of reflective material include metals, such as aluminum,palladium, platinum, titanium, chromium, silver, nickel-based alloys andstainless steel, with a high reflector (having a reflectance greaterthan about 70%), like silver or aluminum, being preferred. However,where resistance to scratching and environmental degradation is aconcern, a medium reflector (having a reflectance within the range ofabout 40% to about 70%), like chromium, stainless steel, titanium andnickel-based alloys, is preferred. As an alternative to the use of thesemetals as a reflective element, multi-coated thin film stacks ofinorganic oxides, halides, nitrides or the like, or a thin film layer ofhigh index material may also be used.

The conductive electrode coatings 4, 4′ may be thin films of metal, suchas silver, aluminum and the like, with a thickness of less than about200 Å, which may be as low as less than about 100 Å, so that theconductive electrode coatings 4, 4′ are sufficiently conductive yetsufficiently transmissive. It may be desirable to index match a thinfilm of metal through the use of a thin film layer of a transparentmetal oxide, metal nitride, metal halide or the like, such as indiumoxide, zinc oxide, tin oxide, magnesium fluoride, titanium nitride,silicon dioxide, tungsten oxide or titanium dioxide, either as anovercoat or an undercoat to the thin film of metal to assist in reducingits reflectance, and increasing its transmittance, of incident visiblelight [see e.g., commonly assigned U.S. Pat. No. 5,239,406 (Lynam)(“Lynam VI”)].

For example, a layer of a metal, such as silver, preferably having athickness of less than about 200 Å and a sheet resistance of less thanabout 12 ohms per square (more preferably, less than about 10 ohms persquare, and most preferably, less than about 8 ohms per square), may beovercoated with a metal oxide transparent conductor [such as a thin filmlayer of indium oxide (itself either undoped or doped with tin to formindium tin oxide)] and/or undercoated with a metal oxide layer [such asa thin film layer of indium oxide (itself either undoped or doped withtin to form indium tin oxide)] to form a substantially transmittingmulti-layer transparent conductor on a glass surface. The sheetresistance of the multi-layer transparent conducting stack is preferablyless than about 10 ohms per square, more preferably less than about 8ohms per square, and most preferably less than 6 ohms per square. Thetransmission of visible light through the multi-layer transparentconductor coated glass substrate (which ordinarily comprises glass/metaloxide/metal/metal oxide or glass/metal/metal oxide such that theoutermost metal oxide layer overcoating the thin metal layer serves as abarrier coating to reduce or prevent direct contact between thepotentially electrochemically vulnerable metal layer and anyelectroactive medium, such as an electrochemically active liquid,thickened liquid and the like, that contacts the multi-layer transparentstack) is preferably greater than about 70%, more preferably greaterthan about 80%, and most preferably greater than about 85%.

Though silver is a preferred metal in such multi-layer transparentconducting stacks, aluminum may also be employed, particularly where theoptical design of the multi-layer stack is optimized to maximize overalllight transmission. Also, the outermost overcoating metal oxide layershould be at least somewhat, and preferably significantly, conducting soas not to form an electrical insulating overcoat on the metal layer. Thesheet resistance for such a metal oxide layer should be less than about2,000 ohms per square, with less than about 1,000 ohms per square beingpreferred and less than about 500 ohms per square being more preferred.This overcoating metal oxide layer may be any at least partiallyconducting, substantially transparent metal oxide such as tin oxide(doped or undoped), indium oxide (doped or undoped), zinc oxide (dopedor undoped) and cadmium stannate. The thickness for the overcoatingmetal oxide layer (as well as the thickness of any undercoating metaloxide layer) is preferably less than about 500 Å, more preferably lessthan about 300 Å, and most preferably less than about 200 Å.

Such multi-layer transparent conducting stacks are preferably depositedusing in-line sputter deposition chambers with either planar or rotarymagnetron targets, and with deposition of the metal oxide layers beingachieved either by reactive deposition of an oxide coating by sputteringfrom a metal target (or from a conductive, pressed oxide target) in anoxygen-rich atmosphere, or by radio-frequency (“RF”) sputtering from anoxide target. An example of a multi-layer transparent conducting stackis glass/ITO/Ag/ITO, with the thickness of the ITO layers being in therange of about 100 to about 300 Å and the thickness of the silver layerbeing in the range of about 80 to about 200 Å.

An economical electrochromic rearview mirror may be fabricated by usingclear glass as a front substrate, substrate 2, (preferably constructedfrom float glass) which is coated on its inwardly facing surface with asubstantially transmitting, multi-layer transparent conductor comprisingat least a thin metal layer overcoated with a transparent conductormetal oxide. For instance, a soda-lime glass substrate coated withindium tin oxide (having a thickness of about 150 Å)/silver (having athickness of about 150 Å)/indium tin oxide (having a thickness of about150 Å) may be used for the front substrate, substrate 2. The rearsubstrate, substrate 3, is coated with a metal reflector (such assilver, aluminum, chromium, titanium, nickel-based alloys likeHastelloy, iron-based alloys like stainless steel, and the like), whichalso serves as the electrical conductor on substrate 3. Anelectrochromic medium is disposed between the two confronting inwardlyfacing conductor surfaces. An example of such a construction isglass/indium tin oxide (having a thickness of about 150 Å)/silver(having a thickness of about 150 Å)/indium tin oxide (having a thicknessof about 150 Å)//electrolyte//tungsten oxide (having a thickness ofabout 6,000 Å)/aluminum (having a thickness of about 2,000 Å)/chromium(having a thickness of about 1,000 Å)/glass, which construction iseconomical to manufacture as the total thickness of the metal oxidetransparent conducting ITO layer is only about 300 Å. This totalthickness compares favorably to the use of a half wave or full wave ITOlayer with a thickness of about 1,500 Å or 3,000 Å, respectively.

The sheet resistance of the conductive electrode coated glass substrates2, 3 should be less than about 100 ohms per square, with less than about20 ohms per square being preferred. (However, as described in greaterdetail hereinafter, for reasons of economy it may sometimes bepreferable to use substantially transparent conductive electrodes havinga sheet resistance of greater than about 20 ohms per square.) Conductiveelectrode coated glass substrates are available commercially. Forinstance, ITO-coated glass substrates made from a glass substrate havingdeposited thereon a conductive coating of indium oxide that has beendoped with tin oxide may be obtained from Donnelly Corporation, Holland,Mich. In addition, tin oxide-coated glass substrates, known as“TEC-Glass” products, may be obtained from Libbey-Owens-Ford Co., LOFGlass Division, Toledo, Ohio.

The “TEC-Glass” products are manufactured by an on-line chemical vapordeposition process: This process pyrolytically deposits onto clear floatglass a multi-layer thin film structure, which includes amicroscopically thin coating of fluorine-doped tin oxide (having a finegrain uniform structure) with additional undercoating thin film layersdisposed between the fluorine-doped tin oxide layer and the underlyingglass substrate. This structure inhibits reflected color and increaseslight transmittance. The resulting “TEC-Glass” product is anon-iridescent glass structure having a haze within the range of fromabout 0.1% to about 5%; a sheet resistance within the range of fromabout 10 to about 1,000 ohms per square or greater; a daylighttransmission within the range of from about 77% to about 87%; a solartransmission within the range of from about 64% to about 80%; and aninfrared reflectance at a wavelength of about 10 μm within the range offrom about 30% to about 87%. See e.g., U.S. patent application Ser. No.08/061,742, filed May 17, 1993, now U.S. Pat. No. 5,424,865, thedisclosure of which is hereby incorporated herein by reference.

Examples of the “TEC-Glass” products include “TEC 10” (10 ohms persquare sheet resistance), “TEC 12” (12 ohms per square sheet resistance)and “TEC 20” (20 ohms per square sheet resistance) tin oxide-coatedglass. More specifically, “TEC 10”, for instance, is made from anon-line pyrolytically-coated float glass, onto which has been coated afluorine-doped tin oxide layer containing as an undercoat ananti-iridescence means. This anti-iridescence means includes a doublelayer composed of a layer of silica-silicone deposited onto a layer oftin oxide.

The specific resistivity of the conductive electrode coatings 4, 4′useful in the present invention may be between about 5×10⁻³ to about1×10⁻⁶ ohm. centimeter, depending on the material from which theconductive electrode coatings 4, 4′ are constructed, and on the methodof deposition and formation of the conductive electrode coatings 4, 4′.For instance, where the conductive electrode coatings 4, 4′ are ITO, thespecific resistivity is typically within the range of about 1×10⁻⁴ toabout 3×10⁻⁴ ohm. centimeter. And where the conductive electrodecoatings 4, 4′ are doped tin oxide, the specific resistivity istypically within the range of about 3×10⁻⁴ to about 5×10⁻³ ohm.centimeter. Where the conductive electrode coating 4′ is a metal, thespecific resistivity is typically less than about 5×10⁻⁵ ohm.centimeter. And where the conductive electrode coating 4′ is silver, thespecific resistivity is typically less than about 3×10⁻⁵ ohm.centimeter. The thickness of the metal should be such that the sheetresistance of conductive electrode coating 4′ is less than about 0.75ohms per square, preferably less than about 0.5 ohms per square and morepreferably less than about 0.25 ohms per square. Preferably, thethickness of the metal used for conductive electrode coating 4′ shouldbe within the range of about 200 Å to about 5,000 Å, with a thicknesswithin the range of 500 Å to about 2,500 Å being preferred and athickness within the range of about 750 Å to about 1,500 Åbeing mostpreferred.

The substantially transparent conductive electrode coating 4 on theinward surface of substrate 2 is preferably highly transmissive in thevisible spectrum; that is, with a light transmittance within the rangeof at least about 60% to greater than about 80%. Likewise, when theconductive electrode coating 4′ on the inward surface of substrate 3 isto be highly transmissive, similar high light transmittance isdesirable.

The conductive electrode coatings 4, 4′ should also be highly anduniformly conductive in each direction to provide a substantiallyuniform response when a potential is applied to the electrochromicelement 1. And, the conductive electrode coatings 4, 4′ should be inert(physically, chemically and electrochemically inert) to the constituentsof the electrochromic solid film 7 and the electrolyte 6.

Where the electrochromic solid film 7 is deposited as a coating onto theinward surface of either of conductive electrode coated glass substrates2, 3, it is a barrier coating between whichever of the conductiveelectrode coatings 4, 4′ it is deposited on and the electrolyte 6, aswell as a barrier coating between the conductive electrode coatings 4,4′ themselves.

The electrochromic solid film 7 may be deposited using a variety of filmdeposition means including, but not limited to, vacuum depositiontechniques, such as thermal evaporation, electron beam evaporation,sputter deposition, ion plating, laser-assisted deposition,microwave-assisted deposition and ion-assisted deposition; thermalspraying; pyrolytic deposition; chemical vapor deposition (“CVD”),including atmospheric CVD, plasma enhanced CVD, low pressure CVD and thelike; wet chemical deposition, including dip coating, spin coating andspray coating; and thick film methods such as those used in theapplication of pastes and inks. Suitable deposition results may beobtained with wet chemical deposition as taught by and described in U.S.Pat. No. 4,855,161 (Moser); U.S. Pat. No. 4,959,247 (Moser); U.S. Pat.No. 4,996,083 (Moser); U.S. Pat. No. 5,252,354 (Cronin) and U.S. Pat.No. 5,277,986 (Cronin), the disclosures of each of which are herebyincorporated herein by reference.

It may be beneficial to deposit the electrochromic solid film usingvacuum deposition, preferably with an electron beam evaporationtechnique where the electrochromic solid film 7 is tungsten oxide and isto be placed in direct contact with, or deposited (for example, with analternate evaporation filament, crucible, boat or an alternate electronbeam gun assembly, or the like) as a layer on, the inward surface ofsubstrate 3, which is already coated with a layer of reflective materialthat serves the dual role as a reflective element and a conductiveelectrode coating 4′.

The layer of reflective material, which also serves as a conductiveelectrode coating 4′, with or without any adhesion enhancing undercoatlayers (discussed hereinafter), may be deposited on the inward surfaceof substrate 3, with tungsten oxide deposited as an overcoat, withoutthe need to refixture, break vacuum or the like. Thus, it is seen thatsuch a dual purpose reflective element may be deposited withmanufacturing ease and economy. This is particularly so when comparedwith conventional mirror constructions where the reflective element iscoated over the rearmost (non-inward) surface of a substrate (whichitself is coated with a substantially transparent conductive electrodecoating on the opposite, inward surface) in one operation, andthereafter loaded into a vacuum chamber to deposit tungsten oxide ontothe other surface of the substrate, which is coated with a substantiallytransparent conductive electrode.

When vacuum depositing the electrochromic solid film 7 by evaporation orthe like, a backfill pressure in a vacuum chamber within the range ofabout 1×10⁻⁴ torr to greater than about 5×10⁻⁴ torr may be used. Thisbackfill pressure may typically be achieved by evacuating the vacuumchamber to some lower base pressure (e.g., less than about 5×10⁻⁵ torr)and then backfilling the vacuum chamber with a gas such as nitrogen,argon, krypton, oxygen, water vapor and the like, or combinationsthereof, to elevate the pressure in the vacuum chamber to a desiredbackfill pressure. Alternatively, the vacuum chamber may be pumped fromatmospheric pressure down to about a pressure within the range of about1×10⁻⁴ torr to greater than about 5×10⁻⁴ torr, and tungsten oxide, forinstance, may then be evaporated onto the desired surface of substrates2, 3. It may be desirable during such vacuum deposition to monitor andto control the pressure within the vacuum chamber using pumps, valvesand closed loop controls as is known in the vacuum deposition art.

It may be useful to maintain a relatively constant backfill gas pressureduring evaporative deposition of the inorganic oxide solidelectrochromic film layer, or of other layers such as an adhesionpromoter layer and a reflector layer. For example, when evaporatingtungsten oxide in the presence of a backfill gas pressure at a desiredset backfill pressure, it is usually desirable to first pump the chamberfrom atmospheric pressure to a base pressure of about 0.1 times thedesired backfill pressure. By so doing, the, backfill pressure shouldremain constant during deposition and not be perturbed by outgasing fromchamber walls, fixtures and, the like.

With reference to FIG. 4, the conductive electrode coatings 4, 4′ in themirror construction so depicted are substantially transparent. Likewise,in the mirror construction depicted in FIG. 7, conductive electrodecoatings 4, 4′ and substrate 3 are substantially transparent.

With reference to FIG. 5, however, only the conductive electrode coating4 of the first substrate 2 in the mirror construction so depicted needbe substantially transparent; that is, the conductive electrode coating4′ need not be substantially transparent. In addition, the secondsubstrate 3 need not be substantially transparent. In this aspect of thepresent invention, the layer of reflective material may be coateddirectly onto the inward surface of the second substrate 3 to serve asthe conductive electrode coating 4′ as well.

Onto one of conductive electrode coatings 4, 4′ is deposited a coatingof an electrochromic solid film 7, such as an inorganic transition metaloxide, like tungsten oxide. As noted herein, where photochromism may bea concern, the electrochromic solid film 7 should be positioned at theinward surface of substrate 3 (which surface is coated with conductiveelectrode coating 4′). By so doing, the electrochromic solid film 7should benefit from the ultraviolet screening and/or absorbingcapabilities of the components of the mirror positioned in front of itand closer to incident light.

Silver or aluminum are suitable choices for conductive electrode coating4′ of substrate 3 because either metal may serve as a reflective elementfor the mirror and metal coatings in general are significantly moreconductive than semiconducting oxides, such as ITO or doped tin oxide.As a consequence of using a thin film of metal as conductive electrodecoating 4′, the substantially transparent conductive electrode coating 4of substrate 2 may be chosen with an eye toward higher sheet resistance,such as, for example, about 40 to about 100 ohms per square. This isdesirable because conductive electrode coatings of higher sheetresistance are typically thinner and less expensive than conductiveelectrode coatings of lower sheet resistance. ITO or doped tin oxide aresuitable choices for substantially transparent conductive electrodecoating 4 used in conjunction with a thin film of metal as a reflectiveelement, such as silver or aluminum, that is to serve as conductiveelectrode coating 4′. In addition, the use of such a thin film of metalas conductive electrode coating 4′ permits the conductive strip or clipconnectors (known as “bus bars”) to be reduced in length, even to apoint contact, on conductive electrode coating 4′, rather than beingused about a substantial portion of the periphery. That is, bus bars 9may be attached at only a portion of the thin film of metal and stillapply an adequate potential across the conductive electrode coatings 4,4′.

Moreover, use of the reflective element of the mirror as the conductiveelectrode coating 4′ is also appealing from a production standpoint.Such use reduces material and manufacturing costs since an additionalelectrode layer or reflective element need not be provided. In addition,this dual purpose reflective element/conductive electrode coating isenvironmentally appealing because it is no longer necessary to enhanceresistance to degradation, such as environmental degradation, byapplying a paint overcoat, which may be lead-based. In addition, suchconventional reflective elements located on the rearmost surface of themirror construction are typically opaque, and, as described hereinafter,such opacity may result in additional manufacturing effort should an “ondemand display” be desirable in a particular mirror construction.

Between the layer of reflective material, typically silver, and thesurface of substrate 3 to which it is applied, may desirably be coated athin film adhesion enhancing means to act as an adhesion promoter(“adhesion promoter”). (See FIG. 6.) The adhesion promoter 11 enhanceslong-term adhesion of the layer of reflective material to the surface ofsubstrate 3. It is known in the art that there are certain difficultiesin adhering a reflective material such as silver to a substrate such asglass, especially where the reflective material is to be deposited by avacuum deposition process such as evaporation. The adhesion promoter 11of the present invention overcomes these difficulties and provides apractical way of applying a coating which will function as a dualpurpose reflective element/conductive electrode in an electrochromicmirror.

Suitable adhesion promoters 11 include thin films of metal and metaloxides that provide enhanced adhesion over a silver to glass interface,such as chromium, stainless steel, nickel-based alloys (e.g.,Hastelloy), titanium, monel, nichrome, molybdenum, metal oxides (e.g.,silver oxide, aluminum oxide, indium oxide, indium tin oxide, tin oxide,doped tin oxide, zinc oxide, doped zinc oxide and chromium oxide) andthe like. The use of thin films of metal or conducting metal oxides(such as indium tin oxide and doped tin oxides) as adhesion promoters asdescribed herein is advantageous in view of their low cost (due to therelative simplicity of evaporating metal onto a surface of a substrateto form metal or metal oxide coatings), their electrical conductivitythat augments that of conductive electrode coating 4′, and theirmechanical hardness. In addition, use of such thin films of metal orconducting metal oxides as adhesion promoters which undercoat the layerof reflective material assist in maintaining the conductivity of the busbars 9. This is particularly advantageous in the event a bus bar (e.g.,a clip connector) should pierce through the layer of reflectivematerial, because the adhesion promoter is a conductive material thatsustains electrical continuity.

An adhesion promoter 11 may be an undercoat of a thin film of a singlemetal, a metal oxide, or a combination of a metal and a metal oxide. Amethod for promoting adhesion of the layer of reflective material to asurface of substrate 3 involves deposition, such as by vacuumevaporation or sputtering of a metal, typically silver, initially in anoxygen-rich atmosphere. In this atmosphere, a thin film of silver oxideis applied onto a surface of substrate 3. Then, by progressivelydecreasing the oxygen atmosphere to zero, a progressively decreasedamount of oxide is formed with respect to the metal content in the thinfilm deposited on the substrate 3. Finally, with little to no oxygenremaining in the atmosphere, a thin film of silver may be built-up uponthe previously formed undercoat of its own oxide/gradient oxide to forman adhesion-promoting layer between the surface of substrate 3 and thelayer of reflective material. Likewise, chromium may be depositedinitially as a thin film of chromium oxide in an atmosphere of enhancedpartial pressure of oxygen, followed by deposition of a thin film ofmetallic chromium by depleting the supply of oxygen. Oxygen may beintroduced again to permit the deposition of silver oxide, and finallywith deposition of a thin film of metallic silver following in an inertatmosphere. The substrate may also be heated, such as to a temperaturewithin the range of from about 100° C. to about 500° C. (and preferablywithin the range of from about 150° C. to about 400° C.), duringreactive deposition of metal to form a metal oxide. Heating thesubstrate in this manner may assist reactive formation of the oxide fromthe metal and may further enhance adhesion. Moreover, a metal oxide,such as chromium oxide, silver oxide, aluminum oxide, indium oxide, tinoxide, titanium oxide or tantalum oxide, may be deposited, such asreactively deposited in an oxygen-rich atmosphere, by vacuum deposition(e.g., evaporation to sputtering) to form adhesion promoter 11.

The adhesion promoter 11 should have a thickness within the range offrom about 10 Å to about 2,500 Å or greater, with about 50 Å to 1,000 Åbeing preferred.

Adhesion promoter 11 can be a single thin film coating or a stack ofthin film coatings. For example, the inward facing surface of substrate3 can first be coated with a conducting metal oxide adhesion promotercoating of indium tin oxide, which in turn is overcoated with a metaladhesion promoter coating of chromium, with this stack in turn beingovercoated with a reflective coating of silver.

In addition to mirrors employing an electrochromic solid film, adhesionpromoter 11 of the present invention may also be used in mirrorsemploying other types of electrochromic technology, such aselectrochromic solution technology of the electrochemichromic type(e.g., Byker I, Byker II, Varaprasad I and Varaprasad III). Thus,adhesion promoter 11 may be used to construct electrochromic mirrorscontaining an electrochromic solution in which a single coating or stackof coatings functions as a dual purpose reflective element/conductiveelectrode.

For some applications, it may be desirable to prevent build-up ofdeposited materials (such as, tungsten oxide and/or silver) at a portionor portions of the inward surface of substrates 2 or 3 inboard from anedge thereof. In this regard, a magnetizable metal mask may be placedover the portion(s) where it is desired to prevent build-up of suchdeposited materials. The magnetizable metal mask may then be held atthat portion of the substrate under a magnetic influence while thematerial is deposited. For example, a magnetizable metal mask may beplaced at the desired location on the inward surface of substrate 3prior to coating the inward surface thereof with an adhesion promoter(e.g. chromium), a layer of reflective material (e.g., silver) and alayer of an electrochromic solid film (e.g., tungsten oxide). A magnetmay be placed on the rearmost surface of substrate 3 behind thatlocation on the inward surface of substrate 3 to ensure that the mask isheld in place. Upon removal of the mask after completion of depositionof the chromium/silver/tungsten oxide stack onto the inward surface ofsubstrate 3, a deposition-free portion of that surface is formed.

As stated supra, the spaced-apart glass substrates 2, 3 have a sealingmeans 5 positioned therebetween to assist in defining the interpanespacing in which the electrochromic solid film 7 and the electrolyte 6are located. The sealing means 5 may be constructed of any materialinert (physically, chemically and electrochemically inert) to theelectrochromic solid film 7 and the components of the electrolyte 6, aswell as to any other material used in the device. To that end, thesealing means 5 may be chosen from the following materials including,but not limited to, various thermosetting materials, such as epoxyresins and silicones, various thermoplastic materials, such asplasticized polyvinyl butyral, polyvinyl chloride, paraffin waxes,ionomer resins, various inorganic materials and the like. For a furtherrecitation of suitable sealing materials, see commonly assigned U.S.Pat. No. 5,233,461 (Doman).

The thickness of the sealing means 5 may vary from about 10 μm to about1,000 μm. Preferably, however, this thickness is about 50 μm to about100 μm.

In addition, the sealing means 5 may prevent escape of the electrolyte6, when in a liquid-phase, from the electrochromic element 1 orpenetration of environmental contaminants into the electrolyte, whetherin a liquid-phase or in a solid-phase. Of course, when the electrolyteis in a solid-phase, leakage or seepage of the electrolyte from themirror is not a concern, but contamination may be.

Desirably, the sealing means 5 comprises a polymer seal formed by thecure of a latent cure adhesive formulation, such as a latent cure epoxy.Such latent cure adhesive formulations, as known in the adhesives arts,comprise an adhesive system (for example, a latent cure epoxy system). Alatent cure adhesive system is sometimes referred to as a one-packagesystem since it is supplied in an uncured or only partially cured formin a single package and thus does not require the mixing together of twoor more components (such as a resin and a separate hardener as is commonwith many adhesive systems like two-component epoxy systems). Thisobviates the need to mix together two or more components when formingthe sealing means 5.

Latent cure epoxies typically have a relatively long pot life (e.g.,hours to days at room temperature), and so do not appreciably set up andharden at room temperature. However, when exposed to an elevatedtemperature (which depends on the chosen resin and latent curing agentand typically, for the preferred systems used in this present invention,with the activation temperature being at least about 60° C., and morepreferably at least about 90° C.), they cure rapidly to attain theirintended cure and bond-strength. Thus, latent cure epoxies have atemperature of activation, below which substantial cure is notinitiated, but above which relatively rapid cure is achieved. Suchsystems may be advantageously employed as the seal material in theelectrochromic cells of the present invention. Also, latent cureadhesives are particularly amenable to commercial scale manufacture ofelectrochromic devices such as electrochromic rearview mirrors (whetherby silkscreening or by direct dispensing from a needle valve dispenser).These latent cure adhesives have a long pot life so that a batch ofadhesive may be used over many hours of production with the assurancethat the adhesive will not unduly age due to room temperature cure(which can lead to inconsistency and potential unreliability in the sealso formed). These latent cure adhesives allow for ease and economy ofmanufacture since by using such one-package, latent cure systems,silkscreens and dispenser systems will not become clogged or obstructeddue to room temperature-induced hardening of the seal adhesive system,and the viscosity of the adhesive system remains relatively constantthroughout the production day. Clean-up is also facilitated due to areduction and near elimination of prematurely hardened adhesive onsilkscreens or within, for instance, dispenser tubing, needles, and thelike.

One-package, latent cure adhesive formulations useful in forming thesealing means 5 may typically include a resin (preferably, an epoxyresin such as EPON Resin 828 commercially available from Shell ChemicalCompany, Houston, Tex.), and a latent curing agent (such as adicyandiamide, a modified amine, an organic acid anhydride, amicroencapsulated amine, an epoxide adduct encapsulated in a polymerizedpolyfunctional epoxide, and an adipic dihydrazide). Latent curing agentsare commercially available, such as from Air Products and ChemicalsIncorporated, Allentown, Pa. under the tradenames ANCAMINE® 2014AS andANCAMINE® 2014FG. These latent curing agents are modified amines. Otherlatent curing agents, such as imidazole-based systems, may also be used.These imidazole-based latent curing agents are also commerciallyavailable from Air Products and Chemicals Incorporated under thetradenames IMCURE® (such as, IMCURE® AMI-2) and CUREZOL™ (such as,CUREZOL™ 2E4MZ, 1B2MZ, 2PZ, C17Z, 2MZ Azine, 2PHZ-5 and 2MA-OK). Also,latent curing agents are commercially available from AJINOMOTOIncorporated, Teaneck, N.J. under the tradename AJICURE®, examples ofwhich include AJICURE® PN-23 and AJICURE® MY-24. Latent cure adhesives,such as latent cure epoxies, optionally and desirably, include fillers(such as, silica-based fillers like IMSIL A-8, which is commerciallyavailable from UNIM Specialty Minerals Incorporated, Elco, Ill., andcalcium carbonate-based fillers like SS-14066 HUBERCARB OPTIFILL, whichis commercially available from J. M. Huber Corporation, Quincy, Ill.),and coupling agents (useful as adhesion promoters) like the silanecoupling agents listed in Table I below:

TABLE I SILANE/ COMMERCIAL SUPPLIER CHEMICAL NAME Z6020, Dow CorningN-(2-aminoethyl)-3-aminop-propyltri- methoxy silane Z6032, Dow CorningN-[2-vinyl,benzylamino-ethyl]-3- aminopropyltrixmethoxy silane Z6076,Dow Corning 3-chloropropyltrimethoxy silane A187, Union Carbideγ-glycidoxypropyltrimethoxy silane A1100, Union Carbideγ-aminopropyltriethoxy silane A174, Union Carbideγ-methacryloxypropyltrimethoxy silane Aldrich Chemicals2-dichloropropyltrimethoxy silane Aldrich Chemicals diphenyldiethoxysilane Q1-6101, Dow Corning proprietary organic trimethoxy silane

Coloring agents (such as, carbon black and heavy metal- or iron-basedpigments) and spacer beads (such as, glass) may also be included. Aparticularly useful latent cure adhesive formulation for the commercialproduction of electrochromic rearview mirrors with good manufacturingeconomics and with excellent double image performance exhibited by themated substrates comprises:

Parts Per Hundred Component Type Parts of Resin Type Resin EPON 8281 —Epoxy Latent Curing ANCAMINE ®2014FG 28 Modified Agent Amine FillerCalcium Carbonate 30 Coloring Agent Carbon Black 1 Spacer Beads Glass 1

This latent-cure adhesive formulation may either be silkscreened to formthe sealing means 5 or may be applied using an automatic fluiddispensing system, such as a high speed, computer controlled fluiddispensing system supplied by ASYMTEK, Carlsbad, Calif. under thetradename AUTOMOVE 400, and the like. Use of a latent curing agent(which produces long-term stability at room temperature but rapid cureat elevated temperatures) in the adhesive formulation used to establishthe sealing means 5 is particularly advantageous w/when using anautomatic fluid dispensing system. In such a system, constancy andcontrol of the fluid viscosity is facilitated, and consistency andprecision of the bead of fluid adhesive dispensed around the perimeterof the substrate is also facilitated. Latent curing agents areparticularly desirable when precision dispensing valves are used, suchas a rotary positive displacement (“RPD”) valve like the DV-06 valvecommercially available from ASYMTEK.

Once the latent cure adhesive is screened or dispensed around the edgeperimeter of a substrate, and after the second substrate is juxtaposedtherewith to establish a cell with an interpane spacing, the latent cureadhesive may be rapidly cured by exposure to elevated temperatures,typically greater than about 60° C. Epoxy adhesive systems that useANCAMINE® latent curing agents and that are cured by exposure to atemperature of at least about 110° C. for a period of time of about onehour, or less, perform excellently. What's more, the cured seal exhibitsresilience when exposed to boiling water for a period of time in excessof 96 hours. The double image performance for such ANCAMINE®-curedmirror cells was also found to be superior to comparable two-componentepoxy systems in that, during typical production of electrochromicrearview mirrors, double imaging measured from cells using the latentcuring agent to effect a cure to form the sealing means 5 wasconsistently lower than comparably processed electrochromic rearviewmirrors which used a two-component epoxy to form the sealing means 5.Also, the glass transition temperature (T_(g)) for the sealing means 5formed by cure of a one-package, latent cure adhesive is preferably lessthan about 140° C., more preferably less than about 120° C. and mostpreferably less than about 100° C.

One package adhesive and sealing systems, that are supplied with alatent curing agent already incorporated in the adhesive formulation,are also commercially available. Such one part curing adhesivesincorporate an integral hardener or catalyst and typically include aliquid epoxy resin and a dicyandiamide hardener. Examples include a onepart epoxy adhesive commercially available from A1 Technology,Princeton, N.J., under the tradenames EH7580, ME 7150-SMT or ME7155-ANC; a one part epoxy adhesive commercially available from AmericanCyanamid, Wayne N.J. under the tradename CYBOND 4802; and a one partepoxy commercially available from CHEMREX, Commerce City, Colo., underthe tradename CHEMREX 7459-9772. Also, one part aerobic adhesive andsealing systems, which depend on oxygen or moisture in the air toactivate or achieve cure, may also be used to form the sealing means 5.An example of such a one part aerobic adhesive and sealing system ismoisture-activated silicone.

Double image performance in rearview mirrors is greatly assisted by theuse of a vacuum-assisted sealing technique. An example of such atechnique is a vacuum bag technique where, spacer means, such as spacerbeads, are disposed across the surfaces of the substrates being mated,and a vacuum is used to better assure substrate to substrate conformity.It is preferable for at least one substrate (usually the first or frontsubstrate) to be thinner than the other, and preferably for at least onesubstrate to have a thickness of 0.075″ or less, with a thickness of0.063″ or less being more preferable, and with a thickness of 0.043″ orless being most preferable. This improvement in double image performanceis particularly desirable when producing convex or multi-radius outsidemirror parts, and when producing large area parts (such as, Class 8heavy truck mirrors), and especially when vacuum backfilling is used intheir production.

Using a vacuum-assisted sealing technique, an uncured sealing adhesive(with spacer beads optionally included therein) may be dispensed aroundthe periphery of a first substrate. Spacer beads, preferably glass beadscapable of withstanding a load, are sprinkled across a surface of thesecond substrate and the first substrate is juxtaposed thereon. Thismated assembly is then temporarily affixed (by temporary clamps, atemporary fixture, and the like), and placed within a vacuum bag (suchas, a heavy duty “MYLAR” bag). The bag is then evacuated to a vacuumusing a vacuum pump. Atmospheric pressure now evenly bears down on thesurfaces of the substrates to be mated forcing conformance of thesubstrates to each other and to the precision glass spacers that areselected to establish the intended interpane spacing. Thetemporarily-fixed assembly (still within the vacuum bag) and thus undera pressure of at least 2 lbs./in² is then placed into an oven which isat atmospheric pressure (or into a heated autoclave which may be atseveral atmospheres pressure) so that the seal adhesive is caused tocure and to set. This may be performed either with vacuum retained bysealing the bag so as to render it airtight or with the hose to thevacuum pump still attached. Once the seal, typically an epoxy, cures andsets, the conformance of the substrates to the spacer beads and to eachother is retained by the now-cured adhesive seal, even when the vacuumbag is vented and the fabricated part removed.

For exterior mirrors that have an area of at least about 140 cm², it isdesirable to place at least some rigid spacer means (such as precisionglass beads) at locations within the interpane space between thesubstrates in the laminate electrochromic cell. Preferably, such spacerbeads are chosen to have a refractive index within the range of about1.4 to about 1.6 so that they optically match the refractive index ofthe substrates (typically glass) and the electrolyte. These rigid spacerbeads not only assist conformity and uniformity of interpane spacing,but also help maintain the integrity of peripheral seals on exteriorrearview mirrors assemblies that use a liquid or thickened liquid. Forinstance, the peripheral seal may burst if an installer or vehicle ownerpresses on the mirror at its center and causes a hydraulic pressurebuild-up at the perimeter seal due to the compression of the fluid orthickened fluid at the part center. Use of such spacer beads,particularly when located at the center of the part within the interpanespace, are beneficial in this regard whether the exterior rearviewmirror is a flat mirror, convex mirror or multi-radius mirror, and isparticularly beneficial when at least the first or front substrate (thesubstrate touched by the vehicle operator or service installer) isrelatively thin glass, such as with a thickness of about 0.075″ or less.Use of, for example, two substrates, each having a thickness of about0.075″ or less, for exterior rearview mirrors, including large areamirrors of area greater than about 140 cm², has numerous advantagesincluding reduced weight (reduces vibration and facilitates manually-and electrically-actuated mirror adjustment in the mirror housing),better double-image performance, and more accurate bending forconvex/multi-radius parts.

Also, for the sealing means 5, it is advantageous to use a somewhatflexible polymer seal material to reduce double imaging from matedsubstrates, and to improve hot/cold thermal shock performance forassemblies using a solid electrolyte. For example, the sealing means 5may be a silicone such as, a one component, black, addition curingsilicone polymer system (like those commercially available from LoctiteCorporation, Newington, Conn. under the tradename VISLOX V-205) or aprimerless, one-part, flowable adhesive that develops a strong,self-priming bond to glass (and coated glass) substrates (like thosecommercially available from Dow Corning, Midland, Mich. under thetradename Q3-6611). Alternatively, a thixotropic, one-part siliconeelastomer adhesive, such as X3-6265 commercially available from DowCorning, may be used to form the sealing means 5. Flexible epoxy resinsmay also be used to form the sealing means 5.

Standard epoxy resins based on bisphenol A and commonly used curingagents are typically brittle and need to be modified to give a tough andflexible cured system. Flexibilization of the resin system may beinternally (commonly referred to as flexibilizing, which may be achievedthrough the use of long-chain aliphatic amines as parts of curingagents; the addition of aminated or carboxylated rubbers; the additionof carboxy-terminated polyesters; the addition of long-chain organiccompounds containing hydroxyl-functional groups; the use of long-chainaliphatic epoxide materials including epoxidized oils), and externallyusing plasticizers. Internal flexibilization is preferable, such as isachieved when a typical epoxy resin (for example, with an epoxideequivalent weight of about 185) is flexibilized by addition of adifunctional primary amine curing agent, such as polyoxypropylenediamine commercially available from Texaco Chemical Company, Houston,Tex. under the tradename JEFFAMINE™ 400, and the like. Desirably, about25-50 parts of any of the above-noted flexibilizers per hundred parts ofresin may be used. Such flexibilized epoxy systems have a % elongationat break within the range of about 50 to about 150, compared to lessthan about 10, for rigid epoxies. In addition, urethane adhesivesystems, such as FLEXOBOND 431 (which is a clear, two-part urethanesystem, commercially available from Bacon Industries, Watertown, Mass.)may be used.

Optionally, and desirably when oxygen permeable seal materials such assilicones are used, a double-seal may be used. In this case, a firstseal (often, the inner seal when silicone and flexible systems are used)is screened/dispensed and a second seal of a different material (often,a rigid epoxy when the first seal is flexible) is screened/dispensedseparately and distinctly from the first seal. Thus, for example, a beadof uncured silicone is screened/dispensed inboard, and around, theperimeter of a substrate, and a bead of uncured epoxy is then dispensedoutboard of the silicone bead and around the edge of the substrate.Next, a second substrate is mated with the first substrate so that thedouble seal adhesive is sandwiched therebetween, and then both adhesiveseals are cured in an oven to form the desired cured, double seal.

Also, whether the sealing means 5 is a single seal or a double seal, itmay be desirable for the seal material to comprise a cured conductiveadhesive so that the seal, or at least a portion thereof, may provide,in whole or at least in part, an electrical bus bar function around theperimeter of a substrate of the assembly. When using such a combinedseal and bus bar, care should be taken to avoid electrically shortingthe inward facing surfaces of substrates 2 and 3. To obviate this, aseal construction, such as that shown in FIG. 14-A, may be used. Withreference to FIG. 14-A, substrates 1420 and 1430 are coated on theirinwardly facing surfaces with electrical conductor electrodes 1420′ and1430′. The substrates 1420, 1430 are mated together with the compoundseal 1450. The compound seal 1450 includes a conducting seal layer 1450A(formed, for example, of a conducting epoxy such as is described below)and a non-conducting, electrically insulating seal layer 1450B (formed,for example, of a conventional, non-conducting epoxy), which serves toinsulate the two conducting electrodes from electrically shorting viaconducting seal layer 1450A. Since the compound seal 1450 essentiallycircumscribes the edge perimeter of the part, the conducting seal layer1450A (to which electrical potential may be connected to via theelectrical lead 1490) serves as an electrically conductive bus bar thatdistributes applied electrical power more evenly around and across theelectrochromic medium (not shown) sandwiched between the substrates 1420and 1430.

Where the electrical conductor electrode 1420′, 1430′ on at least one ofthe opposing surfaces of the substrates 1420, 1430 is removed (or wasnever coated) in the region of the peripheral edge (as shown in FIG.14-B), a unitary conducting seal (as opposed to the compound seal ofFIG. 14-A) may be used. Reference to FIG. 14-B shows the electricallyconducting seal 1450A joining the electrical conductor electrode 1430′on the surface of substrate 1430 to a bare, uncoated surface of opposingsubstrate 1420. Since the contact area of the conducting seal layer1450A to the substrate 1420 is devoid of the electrical conductorelectrode 1420′, the conducting seal layer 1450A does not short theelectrodes 1420′ and 1430′. Conducting seal layer 1450A serves the dualrole of bus bar and seal, yielding economy and ease in devicefabrication and production. Conducting seal layer 1450A may form asingle seal for the cell or may be one of a double seal formed, forexample, when a conventional, non-conducting epoxy is used inboard ofthat conducting seal.

Such a construction is particularly amenable to devices, such as thosedepicted in FIGS. 5 and 6. For instance, in a rearview mirror, a fixturecan form a mask around the edge substrate perimeter, while an adhesionlayer of chromium followed by a reflector layer of aluminum followed byan electrochromic layer of tungsten oxide are deposited. Once removedfrom such a coating fixture, the edges, as masked by the coatingfixture, are uncoated and present a bare glass surface for joining via aconductive epoxy seal to an opposing transparent conductor coatedsubstrate. In such a configuration, the conductive seal can serve as abus bar for the transparent conductor coated substrate it contactswithout shorting to the reflector/adhesion layers on the oppositesubstrate. Preferably, a fast curing, single component, silver filled,electrically conductive epoxy adhesive is used in such a construction,such as is commercially available from Creative Materials Incorporated,Tyngsboro, Mass. under the tradename CMI 1063T2A. Alternatively, 102-05Fand 114-11 (also commercially available from Creative MaterialsIncorporated) electrically conductive inks may be used, which aresolvent-resistant, electrically conductive adhesives (with a silvercontent of greater than about 85%, when cured).

Alternatively, a silver conductor polymer thick film composition, suchas the one commercially available from E.I. du Pont de Nemours,Wilmington, Del. under the designation 5025, may be used. Du Pont 5025is a screen-printable conductive ink that has an air dried sheetresistivity of about 12-15 m′Ω/square/mil. Thermoset silver inks mayalso be used, and are preferred over the air dried variety in terms ofconductivity and sealing performance. Such thermoset silver inks aresingle-component, epoxy based inks, typically with a silver contentgreater than about 50%, with greater than about 75% being preferred, andare fired by exposure to a temperature of about 150° C. for a period oftime of about one hour. A suitable thermoset conductive epoxy is 5504N,which is commercially available from Du Pont. Also, electricallyconductive adhesives such as AREMCO-BOND 525 (commercially availablefrom Aremco Products, Incorporated, Ossining, N.Y.), may be used.AREMCO-BOND 525 is an electrically conductive adhesive that cures whenfired at a temperature of about 350° F. for a period of time of aboutone hour.

To enhance the integrity of a long-lasting seal in terms of sealresiliency, any electrochromic solid film 7 deposited toward theperipheral edges of one of the substrates 2, 3 may be removed so that aseal may be formed directly between a conductive electrode coating 4 ofsubstrate 2 and a conductive electrode coating 4′ of substrate 3—i.e.,directly between at least a portion of the conductive electrode coatedglass substrates 2, 3. This may be accomplished, for example, bydepositing tungsten oxide onto larger sheets of glass and then cuttingsubstrates therefrom. By so doing, the tungsten oxide coating extends tothe cut edge of the substrate. A variety of removal means may then beemployed to remove that portion of the coating from the substrate—up toless than about 2 mm to about 6 mm or thereabouts—inward from theperipheral edges of the substrates. These removal means may includechemical removal, such as with water or with a slightly acidic or basicaqueous solution; physical removal, such as with a blade; laser etching;sandblasting and the like. The conductive electrode coatings 4, >>>4′ atthe peripheral edge may also be removed in like fashion along with thetungsten oxide overcoat.

Alternatively, substrates 2, 3 may be pre-cut to a desired size andshape prior to depositing an electrochromic solid film 7 thereon. Thesepre-cut substrates may be loaded into a masking fixture to preventdeposition of the electrochromic solid film 7 a pre-determined distancefrom the edges of the substrates—such as, inward from the edge up toless than about 2 mm to about 6 mm. The masking system may also allowfor small tab-out portions to facilitate electrical connection with theconductive electrode coatings 4, 4′ and the electrochromic solid film 7deposited in one and the same deposition operation. Of course, it may bepossible to employ movable fixturing or to break vacuum and rearrangefixtures should tab-outs not be desired.

Moisture is known to permeate through electrochromic solid films, suchas tungsten oxide. Thus, where sealing means 5 is positioned entirely orpartially over the electrochromic solid film 7, a secondary weatherbarrier 12 may be advantageously employed about the periphery of thejoint of the assembled laminate (see FIG. 5) to optimize seal integritywhich may be compromised by such moisture permeation or permeation ofother environmental degradants. Suitable materials for use as asecondary weather barrier 12 include adhesives, such as silicones,epoxies, epoxides and urethanes, which may be ultraviolet curable, roomtemperature curable or heat curable.

Commercially available adhesives include the cycloalkyl epoxides soldunder the “CYRACURE” tradename by Union Carbide Chemicals and PlasticsCo., Inc., Danbury, Conn., such as the “CYRACURE” resins UVR-6100 (mixedcycloallkyl epoxides), UVR-6105(3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate), UVR-6110(3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate) andUVR-6128 [bis-(3,4-epoxycyclohexyl)adipate], and the “CYRACURE” diluentsUVR-6200 (mixed cycloalkyl epoxides) and UVR-6216 (1,2-epoxyhexadecane);those epoxides commercially available from Dow Chemical Co., Midland,Mich., such as D.E.R. 736 epoxy resin (epichlorohydrin-polyglycolreaction product), D.E.R. 755 epoxy resin (diglycidyl ether of bisphenolA-diglycidyl ether of polyglycol) and D.E.R. 732 epoxy resin(epichlorohydrin-polyglycol reaction product), and the NOVOLAC epoxyresins such as D.E.N. 431, D.E.N. 438 and D.E.N. 439 (phenolicepoxides), and those epoxides commercially available from Shell ChemicalCo., Oak Brook, Ill., like the “EPON” resins 825 and 1001F(epichlorohydrin-bisphenol A type epoxy resins).

Other commercially available adhesives that are particularly well-suitedfor use herein as a secondary weather barrier 12 include those epoxidescommercially available under the “ENVIBAR” tradename from Union CarbideChemicals and Plastics Co., Inc., Danbury, Conn., such as “ENVIBAR” UV1244T (cycloalkyl epoxides).

A secondary weather barrier 12 may be formed around the sealed jointbetween substrates 2, 3 at any point of contact between the sealingmeans 5 and the electrochromic solid film 7, using in the case ofultraviolet curable adhesives, commercially available curing systems,such as the Fusion UV Curing Systems F-300 B and F-450 [Fusion UV CuringSystems, Buffalo Grove, Ill.], Hanovia UV Curing System [Hanovia Corp.,Newark, N.J. ], RC-500 A Pulsed UV Curing System [Xenon Corp., Woburn,Mass.] and a Sunlighter UV chamber fitted with low intensity mercuryvapor lamps and a turntable.

A source of an applied potential may be introduced to the electrochromicelement 1 of the electrochromic minor by the electrical leads 10, whichmay be wire, solder and the like. The electrical leads 10 may typicallybe connected or affixed to bus bars 9, which themselves may typically beconnected or affixed to the conductive electrode coatings 4, 4′. The busbars 9 may be constructed from a variety of conducting materialsincluding metals, alloys, solder such as ultrasonically-applied solder(e.g., Cerasolzer™ manufactured by the Asahi Glass Co., Tokyo, Japan),metal ribbon connecters, conducting polymers (e.g., conducting rubbersand conducting epoxies), conducting frits, such as silver frits [e.g.,silver conductive frit #7713 (commercially available from E.I. du Pontde Nemours and Company, Wilmington, Del.)] and the like. Anon-exhaustive recitation of such conducting materials may be found inLynam IV. Bus bar materials such as conducting silver frits or soldersmay even overlap onto the cut edge of the substrate to facilitateconnection of electrical leads in the flush assemblies of the invention.

An exposed portion of the conductive electrode coatings 4, 4′ may beprovided through displacement in opposite directions relative to oneanother—i.e., laterally from, but parallel to, the cavity which iscreated by the substrates 2, 3 and the sealing means 5—of the substrates2, 3 onto which the bus bars 9 may be affixed or adhered. (See FIG.11A.) In addition, substrates 2, 3 may be off-set to provide an exposedportion of the conductive electrode coatings 4, 4′ through displacementin opposite directions relative to one another followed by perpendiculardisplacement relative to one another. (See FIG. 11B.) The dimensions ofsubstrates 2, 3 may also be such that, for example, substrate 2 may havea greater width and/or length than substrate 3. Thus, simply bypositioning substrates 2, 3 in spaced-apart relationship and so thattheir central portions are aligned will allow for peripheral edges ofthe substrate with greater dimensions to extend beyond the peripheraledges of the substrate with smaller dimensions. Thus, a portion ofconductive electrode coating 4 or 4′ will be exposed, depending onwhichever of substrates 2, 3 is dimensioned with a larger width and/orlength. (See FIG. 11C.)

An exposed portion of the conductive electrode coatings 4, 4′ may alsobe provided in a flush design, where the substrates 2, 3 are sized andshaped to like dimensions. In such a flush design, the first substrate 2and the second substrate 3 may each be notched at appropriate positionsalong their respective edges. The notches so provided present convenientareas for bus bars and/or point contacts to which are connected oraffixed electrical leads 10 for the introduction of an applied potentialthereto.

It may also be desirable to apply a layer of reflective material ontothe inward surface of substrate 3, and with substrate 3 notched in atleast one appropriate position along its edges. In this way, directaccess is available to the conductive electrode coated inward surface ofsubstrate 2. Likewise, substrate 2 may be notched at a positionappropriately spaced from the notch or notches on substrate 3 to provideaccess to the conductive electrode coated inward surface of substrate 3.These notches provide convenient areas for electrical leads 10 to beconnected or affixed, and allow for such connection or affixation to bemade within the overall dimensions of the mirror assembly. For example,one or both of the substrates 2, 3 may be notched along one or moreedges, and bus bars 9 may then be affixed over the exposed portion ofconductive electrode coatings 4, 4′ of substrates 2, 3. Electrical leads10 may then be joined to the bus bars 9. The electrical connection maybe made to the inward surfaces of substrates 2, 3 without requiringfurther electrical connection on the peripheral edge of the mirrorassembly. As such, the electrical connection to conductive electrodecoatings 4, 4′ will be hidden from view by the reflective element and/orthe mirror case or housing.

Alternatively, one or more localized lobe(s) may be provided atappropriate positions along the respective edges of substrates 2, 3 tofacilitate direct access to the conductive coated inward surfaces ofsubstrates 2, 3.

The bus bars 9 may also comprise thin metal films, preferably with athickness within the range of about 500 Å to about 50,000 Å or greater.These thin metal film bus bars may be deposited onto conductiveelectrode 4 and/or 4′ by vacuum deposition, such as by evaporation orsputtering, and typically have a width within the range of about 0.05 mmto about 6 mm (and preferably with a thickness in the range of 0.05 μmto about 5 μm or greater) and are inboard from the perimeter edge of thesubstrate.

To form the thin metal film bus bars, a mask may be affixed over thecentral region of the substantially transparent conductive electrodecoated substrate leaving at least a portion, and preferably most, of theperimeter region unmasked. Then a thin film of metal, such as chromiumand/or silver, or other metals such as copper, titanium, steel,nickel-based alloys, and the like, may be deposited using a vacuumdeposition process across the entire surface, coating both the maskedcentral region and the unmasked perimetal region. Thereafter, the maskmay be removed leaving the central region of the substrate transparentand with a conducting thin metal film bus bar deposited on at least aportion of the perimetal region. For manufacturing economy, it may bedesirable to establish thin metal film bus bars on the inward surface ofsubstrate 2, conductive electrode coating 4′ and electrochromic solidfilm 7 in a unitary vacuum deposition process step. Thus, it may beconvenient to overlay in central alignment, for example, substrate 3(being uncoated glass) onto the substantially transparent conductiveelectrode coated surface of substrate 2, where substrate 3 is sized andshaped about 2 mm to about 4 mm smaller in both length and width thansubstrate 2 (see e.g., FIG. 11C). A peripheral edge of substrate 2 ofabout 2 mm to about 4 mm will then extend beyond the peripheral edge ofsubstrate 3. In this instance, substrate 2 is made, for example, fromITO-coated glass, and substrate 3 is made from clear soda-lime glass.With this configuration, a vacuum deposition process may be used todeposit a thin metal film and, optionally, a metal oxide thereover,across the entire surface.

Upon completion of the deposition process, the substrates 2, 3 may beseparated from one another. The formation of a thin metal film bus barconsisting of a chromium/silver coating about the peripheral edge ofsubstrate 2 may then be seen where, because of its smaller dimensions,substrate 3 has served the role of a mask to the major, central regionof substrate 2 during deposition. That is, when substrate 3 is removed,the major, central region of substrate 2 has not been coated during thedeposition and the transparency of the major, central region ofsubstrate 2 is maintained. Because this thin metal film bus bar ishighly conductive and extends about the entire periphery of substrate 2,electric potential may be supplied by means of a point electricalcontact (optionally with local removal of any metal oxide) without theneed for a large metal clip or ribbon connector wire as has beenconventionally used heretofore. Moreover, because the thin metal filmbus bar consists of a chromium/silver coating it forms a highlyreflective perimeter coating which may be used to conceal any sealand/or electrical connection for the electrochromic cell. [See U.S. Pat.No. 5,060,112 (Lynam), the disclosure of which is hereby incorporatedherein by reference.]

In addition, the surface of substrate 3 which was exposed duringdeposition is now coated with a chromium/silver/tungsten oxide stack,which may be used as the inward surface in forming an electrochromiccell. The cut edge of substrate 3 is also coated with a chromium/silvercoating during the unitary vacuum deposition process due to theinevitable overspray which occurs in such a process. Thischromium/silver coating around the cut edge of substrate 3 may itselfconveniently be used to establish an electrical connection to applypotential to electrochromic solid film 7.

The applied potential may be supplied from a variety of sourcesincluding, but not limited to, any source of alternating current (AC) ordirect current (DC) known in the art, provided that, if an AC source ischosen, control elements, such as diodes, should be placed between thesource and the conductive electrode coatings 4, 4′ to ensure that thepotential difference between the conductive electrode coatings 4, 4′does not change with variations in polarity of the applied potentialfrom the source. Suitable DC sources include storage batteries, solarthermal cells, photovoltaic cells or photoelectrochemical cells.

The applied potential generated from any of these sources may beintroduced to the electrochromic element 1 within the range of about0.001 volts to about 5.0 volts. Typically, however, an applied potentialof about 0.2 volts to about 2.0 volts is preferred to cause theelectrochromic element to dim to a colored state—i.e., to change theamount of light transmitted therethrough. For electrochromic solid filmslike tungsten oxide, the negative polarity of the potential should beapplied onto whichever of substrates 2, 3 the electrochromic solid film7 is deposited.

Also, in constructions where a metal conductor layer or a metalconductor/reflector layer is contacted with an electrochemically activemedium (such as an electrolyte prepared in accordance with thisinvention or an electrochemichromic solution like those disclosed in,for instance, Byker I and Varaprasad I), it is preferable to apply acathodic potential (i.e., a negative applied potential) to the metallayer to achieve coloration of the electrochromic device (e.g., anelectrochromic rearview mirror). In order to bleach such electrochromicdevices, it is preferable to apply a potential of zero volts to themetal conductor layer.

The teaching of the present invention is well-suited for use inelectrochromic mirrors whose functional surface is substantially planaror flat. For example, flat electrochromic mirrors for motor vehicles maybe manufactured with the electrochromic element of the presentinvention.

In addition, the present teaching is well-suited for use inelectrochromic mirrors having a curved functional surface, with a convexcurvature, a compound curvature, a multi-radius curvature, asphericalcurvature, an aspheric curvature, or combinations of such curvature.(See FIG. 13.) Convex electrochromic mirrors for motor vehicles may bemanufactured with the electrochromic element of the present invention,with radii of curvature typically within the range of about 25″ to about250″, preferably within the range of about 35″ to about 120″, as areconventionally known.

Multi-radius mirrors for motor vehicles, such as those described in U.S.Pat. No. 4,449,786 (McCord), may also be manufactured in accordance withthe present invention. Multi-radius mirrors for motor vehicles maytypically be used on the driver-side exterior of a motor vehicle toextend the driver s field of view and to enable the driver to see safelyand to avoid blind-spots in the rearward field of view. Generally, suchmirrors have a region of a higher radius (i.e., substantially planar orflat) closer or inboard to the driver that serves principally as theprimary driver's rear vision function and a region of a lower radius(i.e., more curved) farther or outboard from the driver that servesprincipally as the blind-spot detection zone in the mirror.

In forming spherical mirrors, such as convex exterior mirrors, oraspherical mirrors such as the multi-radius mirror 44 in FIG. 13, theradius of curvature for the substrates to be used for the laminateassembly formed by the electrochromic element 1 between substrates 2, 3should be matched. Moreover, in aspherical mirrors, the two substrates2, 3 in the laminate assembly should be matched so that the local radiusin one substrate, for example in the first substrate 2, is located over,and oriented to align with, its corresponding local radius in the othersubstrate, for example, in the second substrate 3. (See FIG. 13.)

To achieve such radius of curvature matching, a desired shape for thesubstrates of the aspherical mirrors may be cut from a flat substrate ofdimensions greater than that of the desired multi-radius shape. Thisinitial flat substrate (“a flat minilite”) may have a rectangular,square or circular shape, or may be of the general shape of the desiredmulti-radius shape, or any other convenient alternative shape. Glasslites from which the flat minilites may be cut are desirablysubstantially colorless or tinted soda-lime sheets of glass. Inaddition, depending on the particular mirror construction and whetherthe desired bent shape derived from the flat minilite is to be employedas the front substrate 2 or the rear substrate 3, glass lites/flatminilites, from which the desired bent shape may be derived, may becoated with a substantially transparent conductive electrode coating,such as ITO or fluorine-doped tin oxide. As noted supra, fluorine-dopedtin oxide coated glass is commercially available from Libbey-Owens-FordCo. under the “TEC-Glass” tradename.

Once cut, the oversized flat minilites may be bent to the desiredmulti-radius using either conventional slump bending or press bending.Also, individual minilites may be bent to compound curvature or two flatminilites may be bent together as a matched pair. To manufacture amatched pair of bent minilites, two flat minilites may be stacked on topof one another, loaded in a tandem orientation into a bending press andbent together to the desired curvature (which may be spherical oraspherical) in one bending process step.

Where individual bent minilites are to be manufactured, any one bentminilite manufactured in any one bending process step is intended tomatch any other bent minilite. In electrochromic mirrors, it may beadvantageous to use the twin bent minilites manufactured in tandem oneon top of the other in the one bending operation step as a given matchedpair to assemble a laminate construction.

The desired substrates may be cut from bent minilites to the dimensionand shape suitable for use in the intended laminate construction of theparticular electrochromic mirror. To the extent that the cullet trimmedaway from the bent minilite manufactured as described supra conformsleast to the intended radius design, bending oversized minilites isrecommended. However, and particularly where the bending operation is tobe attentively supervised, the desired dimensioned shape may first becut from flat glass lites, with the desired dimensioned shape then bentto the desired multi-radius curvature.

It may be advantageous to cut multi-radius front and rear substratesfrom their respective bent minilites to facilitate proper alignment of alocal radius on the first substrate relative to its corresponding localradius on the second substrate. In this regard, a matched pair of bentminilites may be assembled into a laminate construction with the firstsubstrate laterally displaced from the second substrate, yet sustaininglocal to local radius alignment there between. In addition, should therebe an asymmetry in radius, one perimeter length, LC, of the bentminilite may be identified as the lower radius (more curved) part of theminilite compared with its opposite perimeter length, LF, identified asthe higher radius (more flat) part of that same bent minilite. Likewise,for its twin match in a matched pair of bent minilites, there may existcorresponding LC′ and LF′ perimeter lengths.

Suitable jigs or the like may be used to assemble a laminateconstruction of an electrochromic mirror with their correspondingperimeter lengths aligned. For example, LC may be aligned a fewmillimeters (e.g., 3 mm) inboard relative to LC′ so that their localradii are mutually aligned and the desired electrical connection isestablished along LC′ and LF. This may be accomplished by cutting ameasured portion (e.g., 3 mm) of bent glass away from along LC and LF′and using jigs to align the now-cut edge of LC to the same measureddistance (e.g., 3 mm) inboard from LC′, with the respective substratesjuxtaposed. Because of this alignment, local radius conformity betweenthe substrates in a laminate construction may be established.

Alternatively, the bent minilites may be cut from oversized minilites sothat one cut substrate may be laid on top of another cut substratealigned in substantially flush relationship so that local to localradius conformity may be maintained and electrical connection may beestablished [see Lynam IV, the disclosure of which is herebyincorporated herein by reference].

While not required, the minilites may be sufficiently oversized to allowmore than one substrate to be cut out from a given minilite, if thebending tool is appropriately designed. By so doing, the substratecutting process benefits from economies of scale. For example, twosubstrates may be cut from the one sufficiently oversized bent minilite.These side-by-side matched twin substrates may be used as substrates 2,3 to construct the same electrochromic laminate assembly, or they may beused to serve as a substrate in any electrochromic laminate assembly.

Also, certain substantially transparent conductive electrode coatings,such as doped tin oxides, are aerobically inert, and as such may be bentin an ordinary air atmosphere without taking precautions to excludeoxygen. However, suitable precautions should be taken to avoid anycrazing, hazing or optical deterioration of the conductive electrodecoatings 4, 4′ during the bending process. Other substantiallytransparent conductive electrode coatings, such as ITO, may be bent fromflat sheet stock using techniques such as those described in U.S. Pat.No. 4,490,227 (Bitter), the disclosure of which is hereby incorporatedherein by reference. After or during heat treatment of ITO, such as in abending/annealing process which produces spherical and aspherical shapedsubstrates suitable for assembling laminate constructions forelectrochromic mirrors or when firing ceramic frit bus bar material suchas silver conductive frit #7713 (Du Pont), it may be desirable toestablish a reducing atmosphere, as described in Bitter, such as ahydrogen-rich atmosphere, like that established with forming gas.

Glass lites and minilites may also be manufactured into spherical and/oraspherical shaped substrates without first being coated with aconductive electrode. In such instances, after the spherical and/oraspherical bent minilites or shaped substrates are manufactured, aconductive electrode coating, such as ITO, may thereafter be depositedonto the concave surface of the substrate 2 and the convex surface ofthe substrate 3.

A demarcation means 22 may be used in the multi-radius mirrors asdescribed herein to separate the more curved, outboard region 55 (i.e.,that portion of an exterior driver-side multi-radius mirror outboard andfarthest from the driver) used by the driver principally as theblind-spot detection zone from the less curved, more flat inboard region65 (i.e., closer to the driver) used by the driver principally for theprimary rear vision function. (See FIG. 13.)

The demarcation means 22 may be a black or darkly colored continuousline or closely interspaced dots, dashes or spots (silk-screened orotherwise applied), which divides the outboard region from the inboardregion of the multi-radius mirror. This black or darkly colored dividingline (or its aforestated equivalent) may assist the driver of a motorvehicle to discern the difference between images in the outermost, morecurved region from those in the innermost, more flat region of themirror. The thickness of this dividing line should be within the rangeof about 0.1 mm to about 3 mm, with about 0.5 mm to about 2 mm beingpreferred.

The demarcation means 22 may be constructed from an organic material,such as a polymer like an epoxy; an inorganic material, such as aceramic frit; or a mixed organic/inorganic material. Such demarcationmeans 22 may be constructed to include, far example, an epoxy coupledwith glass spacer beads, or plastic tape or a die cut from plastic tape.The demarcation means may be placed onto the conductive electrodecoatings 4, 4′ of either or both of substrates 2, 3 by silk-screening orother suitable technique prior to assembling the device. Also, thedemarcation means 22 may be applied to any or all of the surfaces ofsubstrates 2, 3—i.e., the inward surfaces of substrates 2, 3 or theopposite, non-inward surfaces of substrates 2, 3. Additives may beincluded in the material used as a demarcation means to provide orenhance color, such as a dark color, like black, or dark blue or darkbrown; to enhance stability (e.g., ultraviolet stabilizing agents suchas described herein); or to increase adhesion (e.g., coupling agents,such as silane-, titanium-, or zirconium-based coupling agents).Alternatively, a dividing line may be established by etching a surfaceof substrate 2 and/or 3 (such as by sand blasting, laser etching orchemical etching) with optional staining of the etched-surface todevelop a dark colored dividing line.

Where ceramic frits are used as a demarcation means and/or where busbars are formed by applying a silver conductive frit [e.g., #7713 (DuPont)] around the periphery and inboard from the edge of the inwardsurface(s) of substrate 2 and/or substrate 3, it may be convenient tosilk-screen or otherwise apply the material to either or both of thesubstrates 2, 3 prior to bending. In this way, the bending operationserves the dual purpose of bending and firing/curing the ceramic fritonto the substrates. In addition, where epoxies or other organic-basedmaterials are used as the demarcation means and/or materials which actas bus bars, it may be convenient to silk-screen or otherwise apply thematerial to either or both of the substrates prior to final cure of thematerial used as the sealing means so that the sealing means, thedemarcation means and/or material which acts as bus bars may befired/cured in one and the same operation step. A dividing line may alsobe established within the cavity formed between substrates 2, 3.

A driver textural warning 23, such as the conventional textural warning“objects in mirror are closer than they appear”, may be included in theoutermost more curved portion 55 of an electrochromic multi-radiusexterior mirror according to this invention. (See FIG. 13.)Alternatively, a driver textural warning may be included in theinnermost less curved region 65. Heretofore, such warnings have beenestablished through sandblasting or as described in O'Farrell.Alternatively, textural warnings may be applied by silkscreening onto asurface of one of the substrates 2, 3 of the mirror assembly or by othersuitable techniques, such as laser etching, onto the reflective elementof the mirror which is coated onto a surface of substrate 3.

On demand displays 14 may be positioned behind the reflective element ofthe mirror (see FIGS. 9 and 10) and become activated by user input or byinput from a sensor, such as a supplementary vision device (e.g.,camera, sensor, proximity detector, blind-spot detector, infrared andmicrowave detector), temperature sensor, fuel sensor, fault detector,compass sensor, global positioning satellite detector, hazard detectoror the like. In addition, a vehicle function (such as a turn signal,hand brake, foot brake, high beam selection, gear change, memory featureselection and the like) may activate the on demand display. The ondemand display may also be activated by a function such as a compass,clock, a message center, a speedometer, an engine revolution per unitmeter and the like. In the context of their use in conjunction withrearview mirrors for motor vehicles, an on demand display, when notactive or activated, should desirably remain at least substantiallyunobservable or undetectable by the driver and/or passengers. Similarly,in other applications with which these on demand displays may bedesirably used, they should remain at least substantially unobservableor undetectable when not activated.

On demand displays 14 should be an emitting electronic display, such asa vacuum fluorescent display, a light emitting diode, a gas dischargedisplay, a plasma display, a cathode ray tube, an electroluminescentdisplay and the like.

Conventionally, the reflective element in electrochromic mirrors isconstructed by coating the rearmost (non-inward) surface of the secondsubstrate 3, with a reflective element using a wet chemical silver linemirror coating. This rearmost surface is typically coated with a layerof silver 8, and then protected with a thin film layer of copper 19which itself is overcoated with a protective material 20, typically apaint such as a lead-based paint. In this construction, the lighttransmissivity through the mirror is substantially opaque—i.e.,substantially less than about 0.01%; To place a display, camera, sensoror the like behind such a conventional mirror, a “window” 13 throughwhich light may pass must be created as described hereinafter.

With reference to FIGS. 8, 9 and 10, it may be seen that on demanddisplay capability may be introduced to a mirror through the window 13that has been previously created therein [typically, by sand blasting,mechanical erosion (e.g., with a spinning rubber), laser etching,chemical etching and the like] by coating a layer of reflectivematerial, such as a thin film of a metal 16 (e.g., a medium reflector,such as chromium, titanium, stainless steel and the like, having athickness preferably less than about 750 Å), onto the rearmost(non-inward) surface of substrate 3 at the portion of the substratewhere the window 13 exists. (See FIG. 10.) It may be preferable to use amedium reflector, such as chromium, titanium, stainless steel and thelike, because such medium reflectors are durable, scratch resistant andresistant to environmental degradation without the need for additionalovercoat layers like paints, lacquers, or other oxide coatings.Nevertheless, such overcoat layers may, of course, be used. Also, a highreflector such as silver or aluminum may be used, if desired. The window13, now being only partially opaque in light transmissivity, issubstantially light reflecting.

This partially transmitting/substantially reflecting window may beestablished through evaporating or sputtering (using vacuum depositiontechniques) chromium metal over the window to a thickness of up to about750 Å. By so doing, light transmittance within the range of about 1% toabout 10% may be achieved, while also achieving light reflectance withinthe range of about 40 t to about 65%. This method, however, introducesincreased manufacturing costs (e.g., by first creating the window in thesilver line-coated rearmost surface of substrate 3 and then vacuumdepositing thereover the thin film of chromium). Also, the differencesin reflectivity between the higher reflectance off the silver reflectiveelement and the lower reflectance off the partially transmitting, lesserreflecting window may be detectable by or noticeable to an observer.

An alternative method involves the use of a partially transmitting(i.e., light transmission within the range of at least about 1%- toabout 20%), substantially reflecting (i.e., light reflectance within therange of least about 40% to greater than about 70%) metal foil orreflector-coated polymer sheet or film 15, such as metalized polymersheet or film, like aluminum or chromium coated acrylic sheet orpolyester “MYLAR” film (commercially available from Du Pont). Such afoil, or sheet or film 15, reflector coated with a thin film of metal 16may be contacted with, or adhered to using an optical adhesive 18,preferably an index matching adhesive such as described hereinafter, thewindow 13 in the layer of reflective material on substrate 3.

Likewise, an appropriately sized glass cover sheet 15 (or a polymercover sheet) which is coated with a thin film of metal 16 that ispartially light transmitting (preferably, about 1% to about 20%), andyet substantially light reflecting (preferably, at least about 40% togreater than about 70%) may be contacted with, or adhered to using anoptical adhesive 18 as described herein, the window 13 in the layer ofreflective material on substrate 3. (See FIG. 9.) The glass cover sheet15 may be any desired shape and should be sufficiently large to at leastcover the entire window 13 created in the silver-coated, rearmostsurface of substrate 3 (which may be suitable to accommodate, forexample, compass displays, like the compass displays described inO'Farrell and Larson).

It may be convenient to coat glass lites with a high reflector, such asa thin film coating of aluminum or silver, to a thickness that achievesthe desired partial light transmittance and substantial lightreflectance. Alternatively, a medium reflector, such as a thin filmcoating of chromium, stainless steel, titanium or the like, may be usedto coat the glass lites.

An inorganic oxide coating, such as silicon dioxide, titanium dioxide,zinc oxide or the like, may also be overcoated onto the thin film metalreflector coating to impart resilience, resistance against environmentaldegradation, enhance scratch resistance and enhance optical performance.Likewise, a thin film of magnesium fluoride, or a combination of thinfilms of dielectric materials such as described supra, may be used toovercoat the thin film metal reflector coating. A clear coat of alacquer, such as an acrylic- or a urethane-based lacquer or the like, isstill another choice which may be used to overcoat the thin film metalreflector coating.

Once formed, the partially transmitting/substantially reflecting glasslites may be subdivided into a multitude of smaller sized cover sheetsto cover the window in the reflector on the rearmost (non-inward)surface of substrate 3. More specifically, a square, circle or rectanglemay be cut to dimensions of about 1 to about 6 mm or larger than thedimensions of the window for the display. The square- orrectangular-shaped glass cover sheets may then be contacted with, oradhered to, the rearmost (non-inward) surface of substrate 3 to coverthe previously established window for the display.

An optical adhesive 18 that is index matched to the refractive index ofglass (i.e., about 1.52) may be used to adhere the glass cover sheet 15to the rearmost (non-inward) surface of substrate 3. Such opticaladhesives maximize optical quality and optical index matching, andminimize interfacial reflection, and include plasticized polyvinylbutyral, various silicones, polyurethanes such as “NORLAND NOA 65” and“NORLAND NOA 68”, and acrylics such as “DYMAX LIGHT-WELD 478”. The glasscover sheet 15 may be positioned with its semitransparent metalreflector coating 16 closest to the rearmost (non-inward) surface ofsubstrate 3 so that the mirror construction comprises an assembled stackof the glass cover sheet 15/semitransparent reflector metal coating16/optical adhesive 18/rearmost (non-inward) surface of substrate 3. Inthis construction, the optical adhesive is used as both an adhesive andas a protectant for the semitransparent metal reflector-coating 16 ofthe glass cover sheet 15. Such a use of semitransparent reflector-coatedglass cover sheets 15/16 lends itself to economical and automatedassembly. Also, the cover sheet may be made from glass that is coatedwith a dichroic mirror or made from polymer reflector material (“PRM”),as described hereinafter.

As an alternative to localized reflector coating with a thin metal filmas shown in FIG. 10, or localized use of cover sheets, foils, films, andthe like as shown in FIG. 9, at the non-inward surface of substrate 3 atwindow 13, similar localized reflector means can be employed at theinward facing surface of substrate 3 at the location of window 13:

An emitting display 14 may also be positioned behind the rearmost(non-inward) surface of the glass cover sheet 15 (which itself ispositioned behind substrate 3 of the electrochromic mirror assembly). Inthis regard, it may be desirable to use a thin glass for the cover sheet15 to minimize multiple imaging and/or double imaging. The thickness ofthe cover sheet need not be thicker than about 0.063″, with suitablethicknesses being about 0.063″; about 0.043″; about 0.028″; about 0.016″and about 0.008″. However, if desired the thickness of the cover sheet15 may be greater than about 0.063″.

Again with reference to FIG. 5, where the layer of reflective materialis coated onto the inward surface of substrate 3, improved opticalperformance may be observed without reducing the thickness of substrate3. In such constructions, a relatively thick glass (having a thicknessof greater than about 0.063″) may be used for substrate 3 with a thinglass (having a thickness of about 0.063″ or less) used for substrate 2while maintaining good mechanical properties due to the relativelygreater stiffness of substrate 3. Improved optical performance may alsobe observed due to the relative closeness of the layer of reflectivematerial (coated onto the inward surface of substrate 3) and thefrontmost (non-inward) surface of substrate 2.

An illustration of this aspect of the present invention may be seenwhere substrate 3 is fabricated from “TEC 10” glass (having a sheetresistance of about 10 ohms per square), with a thickness of about 3 mm,and substrate 2 is fabricated from soda-lime glass (coated with HW-ITOhaving a sheet resistance of about 12 ohms per square as a substantiallytransparent conductive electrode coating 4), with a thickness of about0.043″. In this construction, the fluorine-doped tin oxide surface ofthe substrate 3 fabricated from “TEC 10” glass is positioned inward (andovercoated with a metal reflector/conductive electrode coating 4′) andthe HW-ITO coated surface of substrate 2 is also positioned inward sothat the coated substrates 2, 3 face one another.

A silicon or similar elemental semiconductor material may also be usedas a reflective element 8 coated onto either the rearmost (non-inward)surface or the inward surface of substrate 3. Methods for makingelemental semiconductor mirrors for motor vehicles are taught by anddescribed in commonly assigned co-pending U.S. patent application Ser.No. 07/700,760, filed. May 15, 1991, now U.S. Pat. No. 5,535,056 (“the'760 application”), the disclosure of which is hereby incorporatedherein by reference. Where it is desired that the high reflectance offthe elemental semiconductor reflector be within the range of at leastabout 60% to greater than about 70%, an undercoat of a thin film layerof silicon dioxide between a thin film layer of silicon and the surfaceof the substrate onto which it is coated may be used to enhancereflectivity performance [see e.g., the '760 application, and U.S. Pat.No. 4,377,613 (Gordon) and U.S. Pat. No. 4,419,386 (Gordon), thedisclosures of each of which are hereby incorporated herein byreference].

In addition, the layer of silicon and/or an undercoat of silicon dioxidemay be deposited using techniques such as vacuum deposition, spraydeposition, CVD, pyrolysis and the like. For example, in-line depositionon a float glass line, and preferably in-bath, in-line deposition on afloat glass line (as known in the glass manufacturing art) using CVD maybe employed to deposit silicon layers and silicon/silicon dioxide thinfilm stacks onto float glass to provide a reflector for substrate 3 thatis both highly reflecting and partially transmitting. A furtheradvantage of these elemental semiconductor coatings is that they arebendable.

For example, a glass coated with a reflective element may be constructedby depositing onto a glass substrate a first layer of elemental siliconat an optical thickness of about 6,950 Å, followed by deposition of asecond layer of silicon dioxide at an optical thickness of about 1,050Å, which in turn is followed by deposition of a third layer of elementalsilicon at an optical thickness of about 1,600 Å. Such a constructionhas a luminous reflectance of about 69% before heating and bending; anda luminous reflectance of about 74% after heating and bending. Asubstantially transparent conductive electrode coating, such as dopedtin oxide (e.g., fluorine-doped tin oxide) and the like, may be coatedover the third layer of elemental silicon to construct a highlyreflecting, electrically conducting glass substrate suitable for use inelectrochromic mirrors and electrochromic devices where the coatedsubstrate may be bent without unacceptable deterioration in its opticaland electrical properties. Preferably, reflector-coated substratesconstructed using multi-layer stacks, such as a glass/silicon/silicondioxide/silicon stack (with or without additional undercoating orovercoating stack layers), may be deposited in-bath, on-line onto glassbeing manufactured on a float glass line.

It may also be advantageous to employ bendable reflector-coatedsubstrates and techniques for manufacturing the same as taught by anddescribed in the '760 application, and multi-layer stacks, such as theglass/silicon/silicon dioxide/silicon stack as described supra, with orwithout an additional overcoating of a substantially transparentconductive electrode coating such as fluorine-doped tin oxide and thelike. Bendable coatings may be advantageous in minimizing manufacturingrequirements since depositing a thin film of metal generally requiresthe steps of first bending the non-reflector coated substrate and thencoating the bent substrate with the layer of reflective material.

As described supra, it may be advantageous to construct electrochromicmirrors whose reflective element 8 is located within the laminateassembly. This may be achieved by coating the inward surface ofsubstrate 3 with a layer of reflective material 8, such as silver, sothat the silver coating (along with any adhesion promoter layers 11) isprotected from the outside environment. For example, a layer ofreflective material 8 may be vacuum deposited onto the inward surface ofsubstrate 3 in one and the same process step as the subsequentdeposition of the electrochromic solid film 7 onto substrate 3. Thisconstruction and process for producing the same not only becomes moreeconomical from a manufacturing standpoint, but also achieves highoptical performance since uniformity of reflectance across the entiresurface area of the mirror is enhanced. The thin film stack [whichcomprises the electrochromic solid film 7 (e.g., tungsten oxide), thelayer of reflective material 8 (e.g. silver or aluminum) and anyundercoat layers between the layer of reflective material 8 andsubstrate 3] should have a light reflectance within the range of atleast about 70% to greater than about 80%, with a light transmissionwithin the range of about 1% to about 20%. Preferably, the lighttransmission is within the range of about 3% to about 20%, and morepreferably within the range of about 4% to about 8%, with a lightreflectance greater than about 80%.

The inward facing surface of substrate 3 may be coated with amulti-layer partially transmitting/substantially reflecting conductorcomprising a partially transmitting (preferably, in the range of about1% to about 20%)/substantially reflecting (preferably, greater thanabout 70% reflectance, and more preferably, greater than about 80%reflectance) metal layer (preferably, a silver or aluminum coating) thatis overcoated with an at least partially conducting transparentconductor metal oxide layer [comprising a doped or undoped tin oxidelayer, a doped or undoped indium oxide layer (such as indium tin oxide)or the like]. Optionally, an undercoating metal oxide (or another atleast partially transmitting metal compound layer, such as a metalnitride like titanium nitride) may be included in the stack whichcomprises the multi-layer conductor. This multi-layer conductorfunctions as reflective element 8, and can be overcoated withelectrochromic solid film 7 during fabrication of an electrochromicmirror incorporating on demand displays. Alternatively, the multi-layerconductor described supra may be used on the inward surface of substrate3, with the electrochromic solid film 7 coated onto the inward surfaceof substrate 2.

A light reflectance of at least 70% (preferably, at least 80%) for thereflective element to be used in an electrochromic mirror incorporatingon demand displays is desirable so that the bleached (unpowered)reflectivity of the electrochromic mirror can be at least 55%(preferably, at least 65%) as measured using SAE J964a, which is therecommended procedure for measuring reflectivity of rearview mirrors forautomobiles. Likewise, a transmission through the reflective element of,preferably, between about 1% to 20% transmission, but not much more thanabout 30% transmission (measured using Illuminant A, a photopicdetector, and at near normal incidence) is desirable so that emittingdisplays disposed behind the reflective element of the electrochromicmirror are adequately visible when powered, even by day but, whenunpowered and not emitting, the displays (along with any othercomponents, circuitry, backing members, case structures, wiring and thelike) are not substantially distinguishable or visible to the driver andvehicle occupants.

With reference to FIGS. 9 and 10, emitting displays 14, such as vacuumfluorescent displays, light emitting diodes, gas discharge displays,plasma displays, cathode ray tubes, electroluminescent displays and thelike may also be placed in contact with, or adhered to using an adhesive17, 18 such as an epoxy, the rear of substrate 3. Generally, suchemitting displays may only be observable when powered so as to emitlight.

A variety of emitting displays 14 may be used in this connectionincluding, but not limited to, double heterojunction AlGaAs very highintensity red LED lamps, such as those solid state light emittingdisplay LED lamps which use double heterojunction Al/GaAs/GaAs materialtechnology [commercially available from Hewlett Packard Corporation,Palo Alto, Calif. under the designation “T-1¾ (5 mm) HLMP-4100-4101”].

Alternatively, vacuum fluorescent displays, such as 12V battery drivenhigh luminance color vacuum fluorescent displays may be advantageouslyused (commercially available from Futaba Corporation of America,Schaumburg, Ill. under the designations S-2425G, S-24-24G, S-2396G andS-2397G]. It may also be advantageous to use displays 14 that operateefficiently at about 12V or lower since these voltages are particularlyamenable to motor vehicles. Also, ultrahigh luminance vacuum fluorescentdisplays, suitable for heads-up-display applications in motor vehiclesmay be used with appropriate circuitry, such as Type 3-LT-10GX[commercially available from Futaba Corporation]. Suitable vacuumfluorescent displays are also commercially available from NECElectronics Incorporated, Mountain View, Calif., such as under thedesignation Part No. FIP2QM8S.

It may also be desirable, particularly where the reflective element isat least partially light transmitting, to use a light absorbing means,such as a black-, brown- or blue-colored or other suitably coloredabsorbing coating, tape, paint, lacquer and the like, on portions of therearmost (non-inward) surface of substrate 3 where displays are notmounted. It may be desirable to use substantially opaque, and preferablydark colored tape or plastic film and the like, across the surface ofsubstrate 3, such as by adhering to protective material 20, preferablyacross substantially the entire rear surface, except where any displaysare to be positioned. By so doing, any secondary images or aestheticallynon-appealing mirror case illumination due to stray light emittance fromthe display may be reduced.

Placement of apertures or cutouts in a tape or film backing may expeditethe assembly of such mirrors by guiding the assembler to the point wherethe desired display or displays is to be mounted. The tape or filmbacking may also serve as an anti-scatter means to enhance safety andprevent injury by retaining any glass shards which may result due tomirror breakage, for example caused by impact from an accident.

Suitably colored paints, inks, plastic films or the like may be appliedto the surface of substrate 3 where the display 14 is to be placed tochange or effect the color of the display. Also, the display 14 may beadhered to a surface of the substrate using an adhesive 18, such as anindex matching adhesive 17, 18, that may be dyed to effect color and/orcontrast enhancement in the display [see e.g., Larson, the disclosure ofwhich is hereby incorporated herein by reference].

Generally, and particularly when the electrochromic element is in itsbleached, uncolored state, it may be desirable for the image of thedisplay—e.g., an information display, such as a compass display, a clockdisplay, a hazard warning display or the like—to have a luminance withinthe range of at least about 30 foot lamberts to about 80 foot lamberts(preferably, within the range of at least about 40 foot lamberts toabout 60 foot lamberts), as measured with the display placed behind, andemitting through, the electrochromic mirror and with the electrochromicelement in its fully transmitting, bleached state. With this level ofluminance, such a display may be read easily even with bright ambientlevels of light. Also, the electronic circuitry taught by and describedin Larson may be used to appropriately dim the display to suit nighttimedriving conditions and/or to compensate for any dimming of theelectrochromic element. Generally, at night the luminance of the displayis about 15-40%, preferably about 20-35% that of the daytime value.

During daytime lighting conditions, drivers of motor vehicles mountedwith an electrochromic mirror (interior, exterior or both) benefit fromrelatively high reflectance (at least about 55%, with at least about 65%typically being preferred) when in the bleached “day” state. Any displaypositioned behind the electrochromic mirror should have a sufficientlyhigh luminance to permit the display (which may be digital,alpha-numeric, analog or combinations thereof) to emit therethrough andbe readable. The display 14 should be readable even when ambientconditions within the cabin of a motor vehicle (or outside, whereelectrochromic exterior rearview mirrors are used or where theelectrochromic interior rearview mirror is mounted in a convertible withits top down) are bright, such as midday on a sunny, cloudless day. Themirrors of the present invention may achieve a light reflectance of atleast about 55% for the high reflectance state where a high reflector inthe form of a thin film metal coating is used with a sufficientthickness to allow for light to transmit through the electrochromicelement 1, preferably within the range of about 1% to about 15%transmission, but not exceeding about 30% (as measured using IlluminantA and a photopic detector, with near normal incidence). Morespecifically, where silver is used as a high reflector, the mirrors ofthe present invention may achieve a light reflectance of at least about65% for the high reflectance state with a light transmissiontherethrough within the range of about 1% to about 20% transmission(measured as described supra). The thin film metal coating may have athickness within the range of about 200 Å to about 1,500 Å, preferablywithin the range of about 200 Å to about 750 Å.

It may also be desirable, particularly when used in conjunction withhighly spectrally selective light emitting diodes and the like, to usePRM as a reflector placed between the display 14 and the rearmost(non-inward) surface of substrate 3. PRM is a spectrally selective,substantially reflecting (greater than about 50%) and significantlytransparent polymer reflector material (see T. Alfrey, Jr. et al.,“Physical Optics of Iridescent Multilayered Plastic Films”, Polym.Eng'g. & Sci., 9(6), 400-04 (1969); W. Schrenk et al., “CoextrudedElastomeric Optical Interference Film”, ANTEC '88, 1703-07 (1988); andsee generally U.S. Pat. No. 3,711,176 (Alfrey, Jr.); U.S. Pat. No.3,557,265 (Chisolm) and U.S. Pat. No. 3,565,985 (Schrenk). PRM iscommercially available from Dow Chemical Co., Midland, Mich., such asunder the designation PRM HU75218.03L, which is a 0.125″ thick sheetingmade of multiple polymer layers (e.g., 1305 layers), having differingrefractive indices and transparent/transparent CAP layers. This PRMexhibits a light reflectance of about 58% and a generally neutral lighttransmittance. Another PRM, designated as PRM HU75218.08L, also is a0.125″ thick sheeting, made from multiple polymer layers (e.g., 1305layers), with a light reflectance of about 58%. However, this PRM hastransparent/red CAP layers which results in a transmission which has adistinctly red tint. As such, it may be particularly well-suited for usein conjunction with the mirrors of the present invention that employ intheir construction red light emitting diodes, such as those typicallyemployed in hazard warning devices.

An array of light emitting diodes may be positioned behind a window 13in a mirror with an appropriately sized piece of PRM positioned betweenthe emitting displays 14 and the rearmost (non-inward) surface of thesubstrate 3. By choosing a PRM with a selective transmission whichpermits the passage of the bandwidth of light emitted by the emitter butthat substantially attenuates other wavelengths not within that bandpassof light, optical efficiency may be enhanced. Indeed, PRM itself may bean appropriate reflective element behind which display emitters may bedisposed. While PRM may be vulnerable to scratching and susceptible todegradation from environmental exposure, substrates 2, 3 offer desirableprotection from such damage. Use of PRM where the piece of PRM is largerthan and covers the window created in the reflective element onsubstrate 3 (but is smaller than the entire surface area of substrate 3)is particularly attractive compared to the use of conventional dichroicmirrors [such as thin film dielectric stack dichroic mirrors(commercially available from Optical Coatings Labs, Santa Rosa, Calif.)]as the reflective element because of economic benefits.

Should it be desirable to use a PRM/emitting display, a substrate withor without a thin film of metal reflector coating that is substantiallytransmitting may be positioned in front of the PRM. Suitable opticaladhesives, preferably index matching adhesives as described supra, maybe used to construct a mirror that comprises a light emitting elementwhich emits light through a sheet of PRM, which is positioned behind aglass substrate through which the emitted light also passes. Such amirror would appear reflective when the light emitting element (e.g., ared LED such as described supra) is unpowered, yet would efficientlydisplay a warning indicia when the light emitting element is powered,strobed or flashed. Also, PRM being a polymer material is relativelyeasily formed by molding, slumping, bending and similar polymer formingmethods, so conformance to a compound curvature or convex curvature isfacilitated.

In that aspect of the present invention directed to exterior rearviewmirrors for motor vehicles, it may be advantageous to use in conjunctiontherewith signal lights, security lights, flood lights, remote actuationand combinations thereof as taught by and described in commonly assignedco-pending U.S. patent application Ser. No. 08/011,947, filed Feb. 1,1993 (“the '947 application”), now U.S. Pat. No. 5,371,659, thedisclosure of which is hereby incorporated herein by reference.

In accordance with the disclosure of U.S. patent application Ser. No.08/011,947, filed Feb. 1, 1993 (“the '947 application”), now U.S. Pat.No. 5,371,659, a personal safety feature is provided for a vehicle inthe form of a floodlight adapted to projecting light generallydownwardly on an area adjacent a portion of the vehicle in order tocreate a lighted security zone in the area. Advantageously, thefloodlight is preferably positioned in the housing of an exterior mirrorhaving a reflective element also positioned in the housing. According toan aspect of the disclosure of U.S. patent application Ser. No.08/011,947, filed Feb. 1, 1993 (“the '947 application”), now U.S. Pat.No. 5,371,659, an actuator is provided for the floodlight including abase unit in the vehicle and a remote transmitter. The base unit isresponsive to a signal from the remote transmitter in order to actuatethe floodlight. This allows the vehicle operator to actuate thefloodlight from a distance in order to establish the security zone priorto approaching the vehicle.

According to another aspect of the disclosure of U.S. patent applicationSer. No. 08/011,947, filed Feb. 1, 1993 (“the '947 application”), nowU.S. Pat. No. 5,371,659, an actuator for the floodlight includes alockout device in order to prevent actuation of the floodlight duringoperation of the vehicle. According to yet a further aspect of thedisclosure of U.S. patent application Ser. No. 08/011,947, filed Feb. 1,1993 (“the '947 application”), now U.S. Pat. No. 5,371,659, a signallight that is adapted to projecting light generally rearwardly of thevehicle is included in the exterior mirror housing. An actuator for thewarning light is connected with the stoplight circuit, turn signalcircuit, or both the stoplight and turn signal circuit, of the vehiclein order to actuate the warning light when either the stoplight or turnsignal is being actuated.

According to yet another aspect of the disclosure of U.S. patentapplication Ser. No. 08/011,947, filed Feb. 1, 1993 (“the '947application”), now U.S. Pat. No. 5,371,659, the floodlight is adapted toprojecting a pattern of light from the housing on an area adjacent aportion of the vehicle that extends laterally onto the vehicle anddownwardly and rearwardly of the vehicle. In this manner, a securityzone is established from the vehicle door to the rear of the vehicle.The signal light is adapted to projecting a pattern of light extendinglaterally away from the vehicle and rearwardly of the vehicle. In thismanner, the pattern generated by the signal light cannot besubstantially observed by a driver of the vehicle. However, the patterngenerated by the signal light may be observed by a driver of anothervehicle passing the vehicle equipped according to the invention.

The floodlight and signal lights may be generated by a light emittingdiode positioned in the housing, a vacuum fluorescent lamp positioned inthe housing, an incandescent lamp positioned in the housing or a lightsource in the vehicle and a light pipe between the light source and themirror housing.

By providing a lighted security zone adjacent the vehicle, users canobserve suspicious activity around the vehicle. The pattern of lightgenerated by a security light according to the invention establishes asecurity zone around, and even under, the vehicle in the important areawhere the users enter and exit the vehicle. The provision for remoteactuation of the security light provides a deterrent to ward off personslurking around the protected vehicle while the users are still at a safedistance from the vehicle. The provision for a lockout circuit ensuresthat the security light will not inadvertently be actuated while thevehicle is in motion. The disclosure of U.S. patent application Ser. No.08/011,947, filed Feb. 1, 1993 (“the '947 application”), now U.S. Pat.No. 5,371,659, further, conveniently combines a signal light that actsin unison with the vehicle's turn signal, brake light, or both, with thesecurity light in an exterior mirror assembly. The signal light may bedesigned to be observed by other vehicles passing the equipped vehiclebut not directly by the driver of the equipped vehicle.

The electrochromic mirrors of the present invention may also include ananti-reflective means, such as an anti-reflective coating, on the front(non-inward) surface of the outermost or frontmost substrate as viewedby an observer (see e.g., Lynam V); an anti-static means, such as aconductive coating, particularly a substantially transparent conductivecoating, such as ITO, tin oxide and the like; index matching means toreduce internal and interfacial reflections, such as thin films of anappropriately selected optical path length; and/or light absorbingglass, such as glass tinted to a neutral density, such as “GRAYLITE”gray tinted glass (commercially available from Pittsburgh Plate GlassIndustries) and “SUNGLAS” gray tinted glass (commercially available fromFord Glass Co., Detroit, Mich.), which assists in augmenting contrastenhancement. Moreover, polymer interlayers, which may be tinted gray,such as those used in electrochromic devices as taught by and describedin Lynam I, may be incorporated into the electrochromic mirrorsdescribed herein.

The mirrors of this present invention, particularly rearview mirrorsintended for use on the exterior motor vehicles, may also benefit froman auxiliary heating means used in connection therewith such as thosetaught by and described in U.S. Pat. No. 5,151,824 (O'Farrell) and U.S.patent application Ser. No. 07/971,676, filed Nov. 4, 1992, now U.S.Pat. No. 5,446,576 (“the '676 application”), the disclosures of each ofwhich are hereby incorporated herein by reference. Preferred among suchheating means are positive temperature coefficient (“PTC”) heater padssuch as those commercially available from ITW Chromomatic, Chicago, Ill.These heater pads employ conductive polymers, such as a crystallineorganic polymer or blend within which is dispersed a conductive fillerlike carbon black, graphite, a metal and a metal oxide, [see e.g., U.S.Pat. No. 4,882,466 (Friel)]. The heater pads exhibit a positivetemperature coefficient; that is, their resistance increases when thesurrounding temperature increases. Thus, the heater pads may be used asa self-regulating heating element.

As an alternative to a heater pad, a heater means, such as a resistancelayer or heating film, may be deposited (such as through vacuumdeposition, thick film printing, screen printing, dispensing, contactprinting, flow coating and the like) onto the outward facing surface ofsubstrate 3 (i.e., onto the rearmost surface of an electrochromic mirrorassembly). Suitable heater means include a PTC material, a metal thinfilm layer (such, chromium, molybdenum, a nickel-based alloy likeInconel and Hastelloy, stainless steel, titanium and the like), and atransparent conductor thin film [such as tin oxide (doped or undoped)and indium tin oxide]. Such heater means are disclosed in the '676application.

The heater means referred to above function both to assure rapidcoloration and bleaching of an electrochromic rearview mirror whenoperated at low temperatures, and to remove any frost or dew which mayaccumulate on the outward facing surface of substrate 2 (i.e., theoutermost surface of the rearview mirror that is contacted by outdoorelements like rain, snow, dew and the like). For example, a convex ormulti-radius electrochromic outside mirror for an automobile may befabricated by forming substrate 3 through bending a fluorine-doped tinoxide coated glass substrate (such as a “TEC-Glass” product like “TEC20”, “TEC 12” or “TEC 10”) so that the transparent conductor doped tinoxide thin film coating is located on the concave surface of substrate3. The opposite, convex surface of substrate 3 is coated with a metalreflector layer (such as silver, optionally being undercoated with achromium adhesion promoter layer) and the reflector in turn is contactedwith an electrochromic layer, such as tungsten oxide. This convexsurface reflector coated/concave surface transparent conductor coatedsubstrate 3 is then mated with an equivalently bent substrate 2 that iscoated on its concave (inward facing) surface with a transparentconductor (such as fluorine doped tin oxide), and with an electrolytebetween the mated substrates to form an electrochromic exterior rearviewmirror. Next, bus bars (e.g., a conductive frit, solder or the like) areformed on opposing sides of the transparent conductor thin film heateron the rearmost, concave surface of substrate 3. When connected to the12 volt battery/ignition electrical supply of a vehicle, the transparentconductor thin film heater on the rearmost, concave surface of substrate3 heats the electrochromic medium and defrosts the front, outermost,concave surface of substrate 2.

If a display is to be mounted behind the reflective element, anappropriately sized and shaped aperture through the auxiliary heatingmeans should be used to accommodate the display but not leave portionsof the mirror unheated for de-icing or de-misting purposes. Likewise,should a heat distribution pad be used, such as an aluminum or copperfoil as described in the '676 application, an appropriately sized andshaped aperture should also be provided therein to accommodate suchdisplays. Where apertures are to be included in a PTC heater pad, apattern of resistive electrodes which contact the conductive polymer,which may typically be applied by a silk-screening process as describedin Friel, should be designed to accommodate the apertures in the pad. Inaddition, such a pattern may also be useful to thermally compensate forthe apertures in the pad. Alternatively, the resistiveelectrode/conductive polymer combination may be applied, for example,directly onto the rearmost (non-inward) surface of substrate 3, or ontoa heat distribution pad that is contacted and/or adhered thereto.

It may also be advantageous to provide mirrors in the form of a module,which module comprises the mirror itself and its electrical connectionmeans (e.g., electrical leads); any heater pad (optionally, including aheat distribution pad) and associated electrical connection means; bezelframes; retaining members (e.g., a one-piece plate) and electricalconnection means (see e.g., O'Farrell); actuators [e.g., Model No.H16-49-8001 (right-hand mirror) and Model No. H16-49-8051 (left-handmirror), commercially available from Matsuyama, Kawoge City, Japan] orplanetary-gear actuators [see e.g., U.S. Pat. No. 4,281,899 (Oskamo) andthe '947 application, the disclosures of each of which are herebyincorporated herein by reference] or memory actuators that includememory control circuitry such as Small Electrical Actuator #966/001which includes a 4 ear adjusting ring, 25 degree travel and an add-onmemory control and is available from Industrie Koot B. V. (IKU) ofMontfort, Netherlands; and brackets for mounting the module within thecasing or housing of a mirror assembly such as taught by and describedin the '947 application. Electrochromic mirrors may be assembled usingthese items to provide modules suitable for use with a mirror casing orhousing that includes the electrochromic element, which incorporates thereflective element and any associated components such as heater means,bezel means, electrically or manually operable actuation means, mountingmeans and electrical connection means. These components may bepre-assembled into a module that is substantially sealed from theoutside environment through the use of sealants like silicones, epoxies,epoxides, urethanes and the like. These components may also be formedand/or assembled in an integral molding process, such as with thoseprocesses described in U.S. Pat. No. 4,139,234 (Morgan) and U.S. Pat.No. 4,561,625 (Weaver), each of which describe suitable moldingprocesses in the context of modular window encapsulation. An added-valueelectrochromic mirror module, including the actuators which allowadjustment and selection of reflector field of view when mounted withinthe outside mirror housings attached to the driver-side andpassenger-side of a vehicle, may be pre-assembled and supplied tooutside vehicular mirror housing manufacturers to facilitate ease andeconomy of manufacturing.

Many aspects of the present invention, particularly those relating tothe use of PRM and emitting displays; glass cover sheets, foils and thelike; and thin film metal coatings that are applied locally and that aresubstantially reflecting and partially transmitting, may of course beemployed with non-electrochromic rearview mirrors for motor vehicles,such as conventional prismatic mirrors. For instance, with exteriorrearview mirrors for motor vehicles, a driver-side rearview mirror and apassenger-side rearview mirror may be mounted in combination on a motorvehicle to be used to complement one another and enhance the driver'srearward field of view. One of such mirrors may be an electrochromicmirror and the other mirror may be a non-electrochromic mirror, such asa chromed-glass mirror, with both exterior mirrors benefiting from theseaspects of the present invention. In addition, these aspects of thepresent invention may be employed in connection with a display windowthat has been established in a prismatic mirror.

Substrate 2 may be of a laminate assembly comprising at least twotransparent panels affixed to one another by a substantially transparentadhesive material, such as an optical adhesive as described herein. Thislaminate assembly assists in reducing the scattering of glass shardsfrom substrate 2 should the mirror assembly break due to impact.Likewise, substrates 2, 3 may each be of such a laminate assembly in aglazing, window, sun roof, display device, contrast filter and the like.

Also, the outermost surface of substrate 2 (i.e., the surface contactedby the outdoor elements including rain, dew and the like when, forexample, substrate 2 forms the outer substrate of an interior orexterior rearview mirror for a motor vehicle constructed such as shownin FIGS. 1 to 13) can be adapted to have an anti-wetting property. Forexample, the outermost glass surface of an exterior electrochromicrearview mirror can be adapted so as to be hydrophobic. This reduceswetting by water droplets and helps to obviate loss in optical clarityin the reflected image off the exterior mirror when driven during rainand the like, caused by beads of water forming on the outermost surfaceof the exterior electrochromic mirror assembly. Preferably, theoutermost glass surface of the electrochromic mirror assembly ismodified, treated or coated so that the contact angle θ (which is theangle that the surface of a drop of liquid water makes with the surfaceof the solid anti-wetting adapted outermost surface of substrate 2 itcontacts) is preferably greater than about 90°, more preferably greaterthan about 120° and most preferably greater than about 150°. Theoutermost surface of substrate 2 may be rendered anti-wetting by avariety of means including ion bombardment with high energy, high atomicweight ions, or application thereto of a layer or coating (that itselfexhibits an anti-wetting property) comprising an inorganic or organicmatrix incorporating organic moieties that increase the contact angle ofwater contacted thereon. For example, a urethane coating incorporatingsilicone moieties (such as described in Lynam II, the disclosure ofwhich is hereby incorporated by reference) may be used. Also, to enhancedurability, diamond-like carbon coatings, such as are deposited bychemical vapor deposition processes, can be used as an anti-wettingmeans on, for example, electrochromic mirrors, windows and devices.

It is clear from the teaching herein that should a glazing, window, sunroof, display device, contrast filter and the like be desirablyconstructed, the reflective element 8 need only be omitted from theassembled construction so that the light which is transmitted throughthe transparent substrate is not further assisted in reflecting backtherethrough.

In the aspects, of the present invention concerning electrochromicdevices, particularly electrochromic optical attenuating contrastfilters, such contrast filters may be an integral part of anelectrochromic device or may be affixed to an already constructeddevice, such as cathode ray tube monitors. For instance, an opticalattenuating contrast filter may be manufactured using an electrochromicelement as described herein and then affixing it to a device, using asuitable optical adhesive. In such contrast filters, the constituents ofthe electrochromic element should be chosen so that the contrast filtermay color to a suitable level upon the introduction of an appliedpotential thereto, and no undesirable spectral bias is exhibited.

Also, an electrochromic reflector according to this invention can beused with a refracting means comprising a first refractor and a secondrefractor. The first refractor diverts incident light towards theelectrochromic variably dimmable reflector. The second refractor ispositioned so that light from the first refractor is incident thereonand directs light from the electrochromic reflector towards the observer(typically, the driver of a motor vehicle). A refracting means suitablefor use in accordance with this invention is described in U.K. Patent GB2,254,832B for “A Rear View Mirror Unit”, the disclosure of which ishereby incorporated herein by reference.

A synchronous manufacturing process, such as the one represented in FIG.15, may be used for the production of both interior and exteriorelectrochromic rearview mirrors. For example, uncoated glass shapes(which may be flat shapes, curved shapes or multi-radius shapes) alreadycut to the desired shape and size of the substrate 2 are loaded into theevaporative coater 1500 and a transparent conductor (such as indium tinoxide) is deposited thereon [such as by electron beam evaporation at arate of about 3-5 Å/sec using an oxygen backfill pressure within therange of from about 5×10⁻⁵ torr to about 9×10⁻⁴ torr oxygen partialpressure and with the substrate heated to a temperature within the rangeof about 200° C. to about 450° C.]. Synchronous with this deposition,uncoated glass shapes already cut to the desired shape and size of thesubstrate 3 are loaded into the evaporative coater 1510. An adhesionlayer of chromium, followed by a reflector layer of aluminum, followedby an electrochromic solid film layer of tungsten oxide are thendeposited thereon. After substrate coating is complete, the substrates2, 3 pass to a seal dispensing station 1520 where a high speed,computer-controlled automatic fluid dispensing system (such as AUTOMOVE400) is used to dispense a latent cure, one-package epoxy around theedge periphery of the transparent conductor coated surface of thesubstrate 2. Next, and with the substrates 2, 3 held in fixtures, therespective inwardly-facing surfaces are mated, with the weight of thefixture itself providing a temporary hold to keep the mated surfaces inplace. The sandwiched parts are then moved to a conveyorized oven orlehr 1530, where the latent curing agent in the latent cure epoxy isactivated by exposure to a temperature of at least about 110° C. Uponexiting the conveyorized oven or lehr 1530, the now permanently matedcell is removed from the fixtures (which are themselves reusable) andthe cell is filled and finished at the fill/assembly station 1540. Useof such a synchronous manufacturing process, and particularly when alatent cure epoxy is used which is dispensed by an automatic fluiddispenser, with the epoxy cured in a conveyorized oven or lehr, iswell-suited for economic, high volume, lean manufacturing of products,such as interior and exterior electrochromic rearview mirrors.

Many aspects of the present invention, especially those concerningmirror construction, use of elemental semiconductor layers or stacks(with or without an additional undercoat of silicon dioxide and/or anovercoat of doped tin oxide), PRM, anti-wetting adaptation, synchronousmanufacturing, localized thin film coatings, multi-layer transparentconducting stacks incorporating a thin metal layer overcoated with aconducting metal oxide layer, conducting seals, variable intensity bandpass filters, isolation valve vacuum backfilling, cover sheets and ondemand displays, may of course be incorporated into electrochromicmirrors and electrochromic devices that employ electrochromic technologyfor the electrochromic element different from that which is taught anddescribed herein, such as electrochromic solution technology of theelectrochemichromic type (e.g., Byker I, Byker II, Varaprasad I andVaraprasad III) and electrochromic solid film technology (e.g., the '675application, the '557 application and Lynam I), including electrochromicorganic thin film technology, in which a thin film of organicelectrochromic material such as a polymerized viologen is employed inthe electrochromic element [see e.g., U.S. Pat. No. 4,473,693(Wrighton)].

Also, an electrochromic solid film may be used which is formed of aninorganic metal oxide, such as a semiconductor electrode of transparentpolycrystalline titanium dioxide (TiO₂), to which is attached a redoxspecies (such as a viologen) using a chelate (spacer) such as salicylicacid chemiabsorbed to the TiO₂ by chelation to surface Ti⁴⁺ atoms. Whensuch a solid film [such as is described in Marquerettaz et al., J. Am.Chem. Soc., 116, 2629-30 (1994), the disclosure of which is herebyincorporated herein by reference] is deposited (preferably with athickness of about 0.1 μm to about 10 μm) upon an electronic conductinglayer, such as fluorine-doped tin oxide, an electron donor (TiO₂)—spacer (the salicylic acid bound to the TiO₂)— electron acceptor (theviologen bound to the salicylic acid) heterodyad is formed that iscapable of efficient electrochromic activity. Such donor-spacer-acceptorcomplexes can include multiple acceptors, such as may be formed when asecond acceptor (such as a quinone like anthraquinone) is linked to afirst acceptor (such as a viologen). Such a donor-spacer-acceptor solidfilm can function as an electrochromic solid film, and may beadvantageously employed in the electrochromic rearview mirrors, windows,sun roofs and other devices of this invention.

The electrochromic medium can comprise a variety of electrochromicallyactive moieties attached, such as by chemical bonding, to an organic orinorganic matrix, and/or included in a polymer structure aselectrochromically active sites. For example, an electrochromicallyactive phthalocyanine-based, and/or phthalocyanine-derived, moiety that,preferably, is color-fast and UV stable in both its reduced and oxidizedstate, can be included in the electrochromic medium, preferably as partof a solid film. Electrochromically active phthalocyanines that can beincorporated in a solid, and/or formed as a solid, include transitionmetal phthalocyanines such as zirconium phthalocyanines and molybdenumphthalocyanines, such as described in J. Silver et al., Polyhedron, 8(13/14), 1163-65 (1989), the disclosure of which is hereby incorporatedherein by reference; solid state polymerized phthalocyanines such as areformed by thermal polymerization of dihydroxy(metallo)phthalocyaninecompounds of Group IVa elements as disclosed by K. Beltios et al., J.Polym. Sci.: Part C: Polymer Letters, 27, 355-59 (1989), the disclosureof which is hereby incorporated herein by reference; siliconphthalocyanine-siloxane polymers such as described in J. Davison et al.,Macromolecules, 11(1), 186-91 (January-February 1978), the disclosure ofwhich is hereby incorporated herein by reference; and lanthanidediphthalocyanines such as lutetium diphthalocyanine such as described byG. Corker et al., J. Electrochem. Soc., 126, 1339-43 (1979), thedisclosure of which is hereby incorporated herein by reference. Suchphthalocyanine-based electrochromic media, preferably in solid form and,most preferably, UV stable in both their oxidized and reduced states,may be advantageously employed in the electrochromic rearview mirrors,windows, sunroofs, and other device of this invention.

Once constructed, the electrochromic device, such as an electrochromicmirror, may have a molded casing or housing placed therearound. Thismolded casing or housing may be pre-formed and then placed about theperiphery of the assembly or, for that matter, injection moldedtherearound using conventional techniques, including injection moldingof thermoplastic materials, such as polyvinyl chloride or polypropylene,or reaction injection molding of thermosetting materials, such aspolyurethane or other thermosets. These techniques are well-known in theart [see e.g., Morgan and Weaver, respectively].

Also, where it is desirable to dispense a fluid medium, such as apotentially air-sensitive electrolyte, into the cell cavity (orinterpane spacing) formed between substrates 2 and 3 in an emptyelectrochromic cell (such as an empty electrochromic rearview mirrorcell), a vacuum backfilling method, such as described in Varaprasad IV,may be used.

For example, a vacuum backfill apparatus can be configured with a firstbell-jar chamber capable of receiving an empty electrochromic rearviewcell and a second chamber, separate from the first bell-jar chamber. Thesecond chamber includes a container, such as a crucible, which holds thepotentially air-sensitive electrolyte to be filled into the emptyinterpane cavity of the electrochromic mirror cell in the bell-jarchamber. The second chamber is initially maintained at an atmosphericpressure of inert gas (such as nitrogen). An isolation valve (such as agate valve) separates this second inert gas-filled chamber from thefirst bell-jar chamber, that itself is initially at an atmosphericpressure of ordinary air. After loading an empty cell into the firstbell-jar chamber, a vacuum pump is used to evacuate the air therefrom tocreate a high vacuum (i.e., a low partial pressure of the components ofair such as oxygen, water vapor, carbon dioxide, nitrogen, etc.) withinthe first bell-jar chamber. A high vacuum is also created within theinterpane cavity of the rearview mirror empty cell in the now evacuatedfirst bell-jar chamber. Next, and only when the air within the bell-jarchamber has been substantially removed, the isolation valve between thebell-jar chamber and the electrolyte-containing crucible in the secondchamber is opened. The vacuum pump now pumps on the second chamber topump away the inert gas therein. As a result, both the bell-jar chamberand the second chamber are brought to a high vacuum.

Procedures described in Varaprasad IV for backfilling are now followed.During the venting step, the bell-jar chamber/second chamber is ventedto an atmospheric pressure of inert gas (such as nitrogen). Theisolation valve is then closed, once again isolating the second chamber(now refilled with inert gas) from the bell-jar chamber. Once the secondchamber is again isolated, the bell-jar chamber is opened to an ordinaryroom air atmosphere and the now-filled mirror cell is removed.

In such a vacuum backfilling technique using an isolation valve means,backfilling occurs using an inert gas but the use of an isolation valve(such as a gate valve, sluice valve, port valve, slit valve orequivalent isolation valve) isolates the potentially air-sensitiveelectrolyte from the air atmosphere at those times when the empty cellis inserted, and the filled cell is removed, from the bell-jar chamber.Such use of an isolation valve means during vacuum backfilling using aninert gas allows for the bell-jar chamber to be loaded and unloaded inan ordinary room air environment, while protecting the potentiallyair-sensitive electrolyte from exposure to air. In such an isolationvalve vacuum backfilling apparatus, a suitable dispenser can be used toreplenish the crucible with electrolyte, with the electrolyte beingpumped from an electrolyte reservoir that is maintained under air-tightconditions without being exposed to air. With this arrangement, theelectrolyte is replenished without being exposed to air. Also, as analternative to flooding the second chamber with inert gas when theisolation valve is closed (so as to isolate the electrolyte in thesecond chamber from contact with air), a vacuum can be established(and/or maintained) in this second chamber when the isolation valve isclosed.

Each of the documents cited herein is hereby incorporated by referenceto the same extent as if each document had individually beenincorporated by reference.

In view of the above description of the instant invention, it is evidentthat a wide range of practical opportunities is provided by the teachingherein. The following examples of electrochromic mirrors andelectrochromic devices are provided to illustrate the utility of thepresent invention only and are not to be construed so as to limit in anyway the teaching herein.

EXAMPLES Example 1

An electrochromic interior rearview automotive mirror cell having ashape commonly used for interior rearview mirrors was constructed fromclear HW-ITO-coated glass as the first substrate (having a sheetresistance of about 12 ohms per square), with a tungsten oxideelectrochromic solid film coated over its HW-ITO coating (which iscoated onto the inward surface of the substrate). As the secondsubstrate of the mirror cell, a HW-ITO-coated glass substrate (alsohaving a sheet resistance of about 12 ohms per square) with the ITOcoated onto its inward surface was used. A reflective element was formedby coating a layer of silver onto the rearmost (opposite, non-inward)surface of the second substrate of the mirror cell. The HW-ITO wascoated onto the glass substrates at a thickness of about 1,500 Å; thetungsten oxide electrochromic solid film was coated over the HW-ITOcoating of the first substrate at a thickness of about 5,000 Å; and thesilver was coated onto the rearmost surface of the second substrateusing conventional wet chemical silver line deposition as known in themirror art. The first substrate was positioned in spaced-apartrelationship with the second substrate to form a 88 μm interpane spacingbetween the coated inward surfaces of the substrates. The firstsubstrate was also laterally displaced from the second substrate toprovide a convenient area for bus bar attachment.

We formulated an electrolyte for this mirror cell containing ferrocene(about 0.015 M), phenothiazine (about 0.06 M), lithium perchlorate(about 0.05 M) and “UVINUL” 400 [about 5% (w/v)] in a solventcombination of tetramethylene sulfone and propylene carbonate [in aratio of about 50:50 (v/v)].

We dispensed the electrolyte described above into the mirror cell by thevacuum backfilling method (as described in Varaprasad IV].

Upon application of about 1.4 volts, we observed that the mirror dimmeduniformly and rapidly to a neutral gray colored state. Specifically, weobserved that the mirror dimmed from about 70% reflectance to about 20%reflectance in a response time of about 3.2 seconds. In addition, weobserved that the mirror exhibited a high reflectance in the unpowered,bleached state of about 74.7% and a low reflectance in the dimmed stateof about 5.9%

We made and recorded these observations following the standard procedureJ964A of the Society of Automotive Engineers, using a reflectometer—setin reflectance mode—equipped with a light source (known in the art asStandard Illuminant A) and a photopic detector assembly.

Spectral scans were recorded using a conventional spectrophotometeroperating in reflection mode in both the bleached state [see FIG. 1 andTables II(a) and II(b)] and the colored state at an applied potential ofabout 1.5 volts [see FIG. 2 and Tables III(a) and III(b)].

TABLE II(a) Reflectance Data In The Unpowered, Bleached State WL (nm) 05 10 15 20 25 30 35 40 45 380 14.5 20.4 29.1 38.2 45.9 51.7 56.1 59.561.9 64.2 430 65.9 67.7 68.9 70.4 71.6 72.7 73.6 74.8 75.4 76.2 480 77.077.7 78.1 78.9 79.5 80.2 80.6 80.7 80.7 80.9 530 80.7 80.6 80.0 80.179.4 79.3 78.8 78.5 78.1 77.8 580 77.2 76.9 76.5 75.8 75.1 74.5 74.173.5 72.5 71.9 630 71.4 70.6 70.1 69.4 68.7 67.9 67.2 66.5 65.6 64.9 68064.5 63.6 62.9 62.0 61.3 60.6 60.2 59.6 58.6 57.4 730 57.1 56.6 55.755.0 54.6 53.9 52.5 51.6 51.2 50.7 780 50.5

TABLE II(b) Color Statistics - C.I.E. Convention Using 2 Degree EyeIlluminant x y DomWave Purity Y A 0.4422 0.4172 547.0 3.2 77.0 C 0.30970.3304 549.7 3.8 77.8

TABLE III(a) Reflectance In The Colored State at 1.5 Volts WL (nm) 0 510 15 20 25 30 35 40 45 380 11.4 11.6 11.8 11.5 10.6 9.5 8.6 7.7 6.8 6.1430 5.5 5.0 5.0 5.1 5.6 5.6 5.8 6.0 6.2 6.3 480 6.5 6.7 6.8 6.9 7.0 7.17.2 7.2 7.2 7.3 530 7.4 7.6 7.8 8.0 8.1 8.1 8.0 7.8 7.6 7.4 580 7.3 7.06.8 6.6 6.3 6.1 6.0 5.7 5.6 5.4 630 5.4 5.2 5.2 5.1 5.0 4.9 4.9 4.8 4.84.8 680 4.8 4.8 4.8 4.7 4.8 4.8 4.8 4.8 4.8 4.8 730 4.9 4.9 4.9 5.0 5.15.0 5.1 5.2 5.1 5.2 780 5.4

TABLE III(b) Color Statistics - C.LE. Convention Using 2 Degree Eye at1.5 Volts Illuminant x y DomWave Purity Y A 0.4323 0.4342 545.3 8.5 7.0C 0.3098 0.3499 549.3 8.9 7.1

We also cycled the mirror as described in Table IV below.

TABLE IV Number of Cycle Color/Bleach Cycles Temperature (° C.) Cycle(secs) Voltage 30,000 50 5/5 1.4/0.0 40,000 room temperature 5/5 1.4/0.030,000 −30  5/5 1.4/0.0 90,000 50 5/5 1.6/0.0 11,000 80 30/30 1.4/0.0

After subjecting this mirror to such cycling conditions, we observed thereflectance of the mirror to decrease from about 70% to about 20% in aresponse time of about 3.2 seconds. In addition, we observed the mirrorto have a high reflectance in the unpowered, bleached state of about78.6% and a low reflectance in the dimmed state of about 6.4% when apotential of 1.4 volts was applied thereto. We made and recorded theseobservations using the SAE procedure referred to supra.

We observed that these mirrors exhibited excellent stability totemperature extremes., For example, after storage at temperatures in the80° C.-110° C. range, for periods ranging from about 2 hours to inexcess of 336 hours, performance remained excellent, and, indeed, inaspects such as transition times from low to high reflectance statesperformance was even better after heat exposure.

Example 2

In this example, we used the same electrolyte formulation and anelectrochromic mirror constructed in the same manner as in Example 1,supra.

We introduced an applied potential of about 1.4 volts to the mirror andobserved its center portion to change from a high reflectance of about75.9% to a low reflectance of about 6.3%, which decreased from about 70%reflectance to about 20% reflectance in a response time of about 3.5seconds.

We then subjected this mirror to an accelerated simulation of outdoorweathering conditions to investigate its resilience and stability toultraviolet light. Specifically, we subjected the mirror to about 1300KJ/m² of ultraviolet exposure in an Atlas Ci35A Xenon Weather-o-meter(Atlas Electric Devices Company, Chicago, Ill.), equipped with a Xenonlamp emitting about 0.55 w/m² intensity at about 340 nm. Afteraccelerated outdoor weathering, we observed that the mirror continued tofunction suitably for use in a motor vehicle. We also observed that themirror cycled well. In addition, we observed the high reflectance to beabout 75.2% and the low reflectance to be about 6.9% when a potential ofabout 1.4 volts was applied thereto.

We made and recorded these observations using the SAE procedure referredto in Example 1, supra.

Example 3

The electrochromic mirror cell of this example was constructed fromclear HW ITO-coated glass as the first substrate as in Example 1, supra.However, the second substrate was constructed of ordinary soda-limeglass. Using electron beam evaporation in a vacuum chamber, a layer ofchromium was coated directly onto the inward surface of the second glasssubstrate as an adhesion promoter. Next, and without breaking vacuum, athin film of silver was coated onto the layer of chromium as areflective element, and thereafter (again without breaking vacuum)tungsten oxide was coated over the layer of silver as an electrochromicsolid film. The layer of chromium was coated onto the second substrateat a thickness of about 1,000 Å; the thin film of silver was coated overthe chromium at a thickness of about 1,000 Å; and the tungsten oxide wascoated over the silver at a thickness of about 5,000 Å. The sheetresistance of the silver so undercoated with chromium was about 0.4 to.0.5 ohms per square. As with the mirror cell of Example 1, supra, thefirst substrate was positioned in spaced-apart relationship with thesecond substrate to form an 88 μm interpane spacing between the coatedinward surfaces of the substrates. The first substrate was laterallydisplaced from the second substrate to provide a convenient area for busbar attachment.

We used the electrolyte of Example 1, supra, and dispensed it into themirror cell using the vacuum backfilling method [as described inVaraprasad IV].

We introduced an applied potential of about 1.4 volts to the mirror andobserved the change from a high reflectance of about 81.6% to a lowreflectance of about 5.9%, which decreased from about 70% reflectance toabout 20% reflectance in a response time of about 1.9 seconds.

We made and recorded these observations using the SAE procedure referredto in Example 1, supra.

We also cycled the mirror as described in Table V below.

TABLE V Number Cycle Color/Bleach of Cycles Temperature (° C.) Cycle(secs) Voltage 30,000 50 5/5 1.4/0.0 40,000 room temperature 5/5 1.4/0.0

After subjecting the mirror to such cycling conditions, we observed thereflectance of the mirror in the unpowered, bleached state to be 77.3%,and the mirror dimmed to 6.2% reflectance with 1.4 volts appliedthereto.

Example 4

We used an electrochromic mirror cell constructed in the same format andwith the same shape and dimensions as in Example 1, supra, except that atungsten oxide electrochromic solid film (having a thickness of about5,000 Å) was coated over the HW-ITO coating on the inward surface of thesecond substrate.

We formulated an electrolyte containing ferrocene (about 0.025 M),phenothiazine (about 0.05 M), lithium perchlorate (about 0.05 M) and“UVINUL” 400 [about 10% (w/v)] in a solvent combination oftetramethylene sulfone and propylene carbonate [in a ratio of about25:75 (v/v)]. We dispensed the electrolyte into the mirror cell usingthe vacuum backfilling method [as described in Varaprasad IV].

Upon introduction of an applied potential of about 1.4 volts, weobserved the mirror to dim uniformly and rapidly to a neutral graycolored state. Specifically, we observed the mirror to have a highreflectance in the unpowered, bleached state of about 70.7% and a lowreflectance in the dimmed state of about 7.3%. We made and recordedthese observations using the SAE procedure referred to in Example 1,supra.

We also cycled the mirror and subjected the mirror to an acceleratedsimulation of outdoor weathering conditions to investigate itsresilience and stability to ultraviolet light as described in Example 2,supra, but at an exposure of about over 2,500 KJ/m². We observed thatthe mirror cycled well, and after accelerated outdoor weathering, wealso observed that the mirror continued to function in a manner suitablefor use in a motor vehicle.

Example 5

In this example, we fabricated an electrochromic glazing cell of aconstruction suitable for use as a window or a sun roof for a motorvehicle. The glazing cell was dimensioned to about 15 cm×about 15 cm,with an interpane spacing between the tungsten oxide coating on theinward surface of the second substrate and the HW-ITO coating on theinward surface of the first substrate of about 105 μm.

The glazing cell was constructed using spacers to assist in defining theinterpane spacing. The spacers were sprinkled over the tungstenoxide-coated surface of the first substrate and, inward from theperipheral edge of the HW-ITO-coated second substrate, an epoxy wasapplied using a silk-screening technique. While the epoxy was stilluncured, the first substrate and the second substrate were off-set fromone another by a lateral displacement and a perpendicular displacement.The epoxy was then cured into a seal for the electrochromic glazing cellusing a vacuum bagging technique (as is known in the laminating art) ata reduced atmospheric pressure of about 10″ of mercury and a temperatureof about 110° C. for a period of time of about 2 hours in order toachieve substantially even pressure while curing the epoxy into a seal.

We formulated an electrolyte containing ferrocene (about 0.015 M),phenothiazine (about 0.06 M), lithium perchlorate (about 0.05 M) and“UVINUL” 400 [about 5% (w/v)] in a solvent combination of tetramethylenesulfone and propylene carbonate [in a ratio of about 50:50 (v/v)]. Wedispensed this electrolyte into the electrochromic glazing cell usingthe vacuum backfilling method [as described in Varaprasad IV].

Upon introduction of an applied potential of about 1.4 volts to theelectrochromic glazing, we observed the transmissivity change from ahigh transmittance of about 78.6% to a low transmittance of about 12.9%.

We made and recorded these observations using the SAE procedure referredto in Example 1, supra, except that the reflectometer was set intransmittance mode.

Example 6

In this example, we constructed an electrochromic mirror suitable foruse as an exterior rearview mirror for a motor vehicle.

The mirror was constructed from clear HW-ITO-coated glass as the firstsubstrate as in Example 1, supra.

However, as the second substrate we used ordinary soda-lime glass. Bothsubstrates were sized and shaped to dimensions of 9.5 cm×15 cm. A notchwas cut in one edge of the first substrate, and another notch was cut ina different location on one edge of the second substrate. A bus bar wasformed along the edges of the first substrate by silk-screening a silverconductive frit material [#7713 (Du Pont)] all around the perimetalregion of the HW-ITO-coated surface of the substrate to a width of about2.5 mm, and then firing the frit at an elevated temperature in areducing atmosphere to avoid oxidizing the HW-ITO.

A layer of chromium at a thickness of about 1,000 Å was coated directlyby vacuum deposition onto the inward surface of the second glasssubstrate as an adhesion promoter. Thereafter, without breaking vacuum,a thin film of silver at a thickness of about 1,000 Å was coated ontothe layer of chromium as a reflective element, and tungsten oxide at athickness of about 5,000 Å was then coated (again, without breakingvacuum) over the layer of silver as an electrochromic solid film. Thefirst substrate and the second substrate were then positioned inspaced-apart relationship so that the edges of the substrates wereflush, and a seal was applied so as to form a cavity between the twosubstrates. In this flush design, the interpane spacing between thecoated inward surfaces of the substrates was 88 μm.

For this exterior mirror, we formulated an electrolyte containingferrocene (about 0.025 M), phenothiazine (about 0.06 M), lithiumtetrafluoroborate (about 0.05 M) and “UVINUL” 400 [about 5% (w/v)] inpropylene carbonate. We dispensed this electrolyte into the mirror cellusing the vacuum backfilling method [as described in Varaprasad IV].

Electrical leads were then attached to the mirror. The notch on thesecond substrate permitted an electrical lead to be attached at a pointcontact on the silver frit bus bar formed around and substantiallycircumscribing the perimeter of the HW-ITO-coated inward surface of thefirst substrate. Another electrical lead was attached to the portion ofthe chromium/silver/tungsten oxide coating on the inward surface of thesecond substrate exposed by the notch cut in the first substrate. Thepoint contact was sufficient to apply a potential across the electrodesbecause of the low sheet resistance of the coating on the inward surfaceof the second substrate.

Upon introduction of an applied potential of about 1.5 volts to themirror, we observed the reflectance change from a high reflectance ofabout 77.5% to a low reflectance of about 10.6%.

We also cycled the mirror for about 50,000 cycles at a temperature ofabout 50° C., and observed that the mirror cycled well and continued tofunction suitably for use in a motor vehicle.

Example 7

In this example, we used the same electrolyte formulation and anelectrochromic mirror cell of the same shape as described in Example 1,supra. After filling the electrochromic mirror cell using the vacuumbackfilling method (as described in Varaprasad IV], we removed thetungsten oxide coating from the peripheral edge of the first substrateusing a dilute basic solution of potassium hydroxide followed by water.We then connected the bus bars to this newly-exposed ITO surface.Thereafter we applied a secondary weather barrier material. Thesecondary weather barrier material was formed from “ENVIBAR” UV 1244Tultraviolet curable epoxy, with about 2% of the silane coupling agentA-186 (OSi Specialties Inc., Danbury, Conn.) combined with about 1% ofthe photoinitiator “CYRACURE” UVI-6990. Thereafter, we cured thismaterial by exposing it to a suitable source of ultraviolet light toform a secondary weather barrier.

Once the secondary weather barrier was formed, we introduced an appliedpotential of about 1.3 volts to the mirror and observed the reflectancechange from a high reflectance of about 77.8% to a low reflectance ofabout 7.1%.

We made and recorded these observations using the SAE procedure referredto in Example 1, supra.

We also mounted this electrochromic mirror in the cabin of a motorvehicle and found the mirror to operate in a commercially acceptablemanner.

Example 8

We used an electrochromic mirror cell having the same shape as describedin Example 1, supra, constructed from clear ITO-coated glass as thefirst substrate (having a sheet resistance of about 80 ohms per square).As the second substrate of the mirror cell, we used ordinary soda-limeglass. The first substrate was dimensioned about 2 to about 3 mm largerin both length and width than the second substrate. A layer of chromium,as an adhesion promoter, was coated directly onto the inward surface ofthe second glass substrate at a thickness of about 1,000 Å. A thin filmof silver, as a reflective element, was thereafter coated onto the layerof chromium at a thickness of about 1,000 Å and tungsten oxide, as anelectrochromic solid film, was then coated over the layer of silver at athickness of about 5,000 Å. These thin films were coated in a vacuumdeposition process by electron beam evaporation and were deposited in aunitary deposition process without breaking vacuum during deposition ofthe chromium/silver/tungsten oxide stack.

Also, when a transparent conductor coated substrate (for example,fluorine doped tin oxide coated glass, such as “TEC-Glass” describedsupra, that is bendable in an ordinary air atmosphere) is used for thesubstrate 2, and/or when a bendable reflector-coated substrate (forexample, the combination of a silicon based reflector overcoated with atin oxide transparent conductor described supra), is used for thesubstrate 35 the process outlined in FIG. 15 can be appropriatelymodified. For example, a convex or aspherical exterior mirror shapesuitable for use as the substrate 2 can be cut from a bent minilite of“TEC-20” glass comprising a fluorine doped tin oxide transparentconductor of about 20 ohms per square sheet resistance and with the tinoxide coating located on the concave surface of the bent minilite. Useof such air-bendable transparent conductors, as are conventionallyknown, is an alternate to transparent conductor coating the concavesurface of a bent, plain glass surface, as illustrated in FIG. 15. Also,use of a bendable, elemental semiconductor reflector layer that isitself rendered conducting, or that is overcoated with a transparentconducting layer such as tin oxide, may be used (in lieu of coatingmetal layers) of aluminum, silver, chromium and the like that aretypically non-bendable) on the convex surface of bent substrate 3.

The first substrate and the second substrate were positioned inspaced-apart relationship to form a 88 μm interpane spacing between theITO-coated surface of the first substrate and the multi-layered surfaceof the second substrate. The size and shape differential between thefirst substrate and the second substrate allowed the ITO-coated surfaceof the first substrate to extend beyond the multi-layered surface of thesecond substrate. Bus bars were attached substantially all around theperipheral edge of the ITO-coated first substrate onto which wereconnected the electrical leads. On the multi-layered second substrate,we attached electrical leads at a smaller portion thereof, such as at amere point contact.

We formulated an electrolyte containing ferrocene (about 0.015 M),phenothiazine (about 0.06 M), lithium perchlorate (about 0.05 M) and“UVINUL” 400 [about 5% (w/v)] in a solvent combination of tetramethylenesulfone and propylene carbonate [in a ratio of about 50:50 (v/v)]. Wedispensed this electrolyte into the mirror cell using the vacuumbackfilling method [as described in Varaprasad IV].

Upon introduction of an applied potential of about 1.4 volts, weobserved the mirror to dim uniformly and rapidly to a neutral graycolored state. Specifically, we observed the mirror to have a highreflectance in the unpowered, bleached state of about 75.8% and a lowreflectance in the dimmed state of about 9.5%. We made and recordedthese observations using the SAE procedure referred to in Example 1,supra.

Example 9

In this example, we used the electrolyte formulation and anelectrochromic mirror having the same shape as described in Example 8,supra. However, the mirror of this example was constructed fromITO-coated glass as the first substrate having a sheet resistance ofabout 55 ohms per squares. In addition, the first substrate and thesecond substrate were positioned in spaced-apart relationship to form a63 μm interpane spacing between the ITO-coated surface of the firstsubstrate and multi-layered surface of the second substrate.

After dispensing the electrolyte into the mirror cell using the vacuumbackfilling method [as described in Varaprasad IV], we observed themirror to have a high reflectance of about 75.7% and a low reflectanceof about 8.6% when a potential of about 1.4 volts was applied thereto.We made and recorded these observations using the SAE procedure referredto in Example 1, supra.

Example 10

In this example, we fabricated an electrochromic glazing device of aconstruction suitable for use as a window or a sun roof on a motorvehicle containing a solid electrolyte. The glazing device wasdimensioned to about 15 cm×about 15 cm, with an interpane spacingbetween the tungsten oxide coating on the inward surface of the firstsubstrate and the HW-ITO coating on the inward surface of the secondsubstrate of about 74 μm.

The glazing device was constructed using spacers to assist in definingthe interpane spacing. The spacers were sprinkled over the tungstenoxide coated surface of the first substrate and an epoxy was appliedinward from the peripheral edge of the HW-ITO coated second substrateusing a silk-screening technique. While the epoxy was still uncured, thefirst substrate and the second substrate were off-set from one anotherby a lateral displacement and a perpendicular displacement. The weatherbarrier of the electrochromic glazing device was then formed by thermalcuring using a vacuum bagging technique (as is known in the laminatingart) at a reduced atmospheric pressure of about 10″ of mercury and atemperature of about 140° C. for a period of time of about 1 hour inorder to maintain a substantially even pressure when curing the epoxyinto a weather barrier.

We prepared a formulation of starting components containing ferrocene[about 0.3% (w/w)], phenothiazine [about 0.8% (w/w)], lithiumperchlorate (about 0.4% (w/w)], “SARBOX” acrylate resin (500E50) [about27.9% t (w/w)], propylene carbonate (as a plasticizer) [about 67.3%(w/w)] and “IRGACURE” 184 (as a photoinitiator) [about 3.3% (w/w)]. Wedispensed this formulation into the electrochromic glazing device usingthe vacuum backfilling method [as described in Varaprasad IV].

We then in situ polymerized the formulation by exposing it toultraviolet radiation to form a solid-phase electrolyte.

We then affixed bus bars along the peripheral edges of theelectrochromic glazing device, and connected electrical leads to the busbars.

We introduced an applied potential of about 1.5 volts to theelectrochromic glazing for a period of time of about 2 minutes, with thepositive polarity applied at the second substrate (the surface of whichhaving tungsten oxide overcoated onto its HW-ITO-coated surface) andobserved it to have a high transmittance of about 73.0%. Thereafter, wereversed the polarity, and observed the transmission to dim to a lowtransmittance of about 17.8% when a potential of about 1.5 volts wasapplied thereto.

We made and recorded these observations using the SAE procedure referredto in Example 1, supra, except that the reflectometer was set intransmittance mode.

Example 11

In this example, we constructed an electrochromic mirror device havingthe same shape described in Example 1, supra, with an interpane spacingof about 74 μm and using a solid-phase electrolyte.

We prepared a formulation of starting components containing ferrocene[about 0.2% (w/w)], phenothiazine [about 0.5% (w/w)], lithiumperchlorate [about 0.3% (w/w)], polyethylene glycol dimethacrylate (600)(PEGDMA-600) [about 17.9% (w/w)], propylene carbonate (as a plasticizer)[about 76.5% (w/w)], “IRGACURE” 184 (as a photoinitiator) [about 2.1%(w/w)] and “UVINUL” 400 [about 2.5% (w/w)].

The mirror was constructed using spacers to assist in defining theinterpane spacing. The spacers were sprinkled over the HW-ITO coatedinward surface of the first substrate (whose opposite, non-inwardsurface had been coated with a layer of silver using conventional wetchemical silver line deposition) and the formulation, which would betransformed into a solid-phase electrolyte, was dispensed thereover. Thesecond substrate, whose inward surface was coated with tungsten oxide ata thickness of about 5,000 Å, was positioned over the spacer-sprinkledHW-ITO coated surface of the first substrate to allow the formulation tospread evenly across and between the coated surfaces of the firstsubstrate and the second substrate.

We temporarily held the first substrate and the second substratetogether using clamps and in situ polymerized the formulation locatedtherebetween through exposure to ultraviolet radiation to form asolid-phase electrolyte. Specifically, we placed the mirror onto theconveyor belt of a Fusion UV Curing System F-450 B, with the beltadvancing at a rate of about fifteen feet per minute and being subjectedto ultraviolet radiation generated by the D fusion lamp of the F-450 B.We passed the mirror under the fusion lamp fifteen times pausing for twominute intervals between every fifth pass.

We then affixed bus bars along the peripheral edges of the device, andattached electrical leads to the bus bars.

We introduced an applied potential of about 1.5 volts to theelectrochromic mirror for a period of time of about 2 minutes, with thepositive polarity applied at the second substrate (the surface of whichhaving tungsten oxide overcoated onto its HW-ITO-coated surface) andobserved it to have a high reflectance of about 73.2%. Thereafter, wereversed the polarity, and observed the reflection to dim to a lowreflectance of about 7.1% when a potential of about 1.5 volts wasapplied thereto.

We made and recorded these observations using the SAE procedure referredto in Example 1, supra.

Example 12

In this example, we constructed an electrochromic mirror cell having thesame shape described in Example 4, supra.

We formulated an electrolyte containing ferrocene (about 0.025 M),phenothiazine (about 0.06 M), lithium perchlorate (about 0.05 M) and“UVINUL” 400 [about 5% (w/v)] in a solvent combination of 1,2-butylenecarbonate and propylene carbonate [in a ratio of about 50:50 (v/v)]. Wedispensed this electrolyte into the mirror cell using the vacuumbackfilling method [as described in Varaprasad IV].

Upon introduction of an applied potential of about 1.4 volts to themirror, we observed the high reflectance change from about 72.0% to alow reflectance of about 6.8%.

We also cycled the mirror for about 50,000 cycles at a temperature ofabout 50° C., and observed it to cycle well.

Example 13

In this example, we again constructed an electrochromic mirror cellhaving the same shape described in Example 1, supra.

For this mirror cell, we formulated an electrolyte containing ferrocene(about 0.025 M), phenothiazine (about 0.06 M), lithium perchlorate(about 0.05 M), lithium tetrafluoroborate (about 0.05 M) and “UVINUL”400 [about 5% (w/v)] in propylene carbonate, and dispensed it into themirror cell using the vacuum backfilling method [as described inVaraprasad IV].

Upon introduction of an applied potential of about 1.4 volts to themirror, we observed the high reflectance to change from about 72.0% to alow reflectance of about 6.7%.

The mirror demonstrated excellent cycle stability and stability toultraviolet light.

Example 14

In this example, we constructed an electrochromic mirror cell having thesame shape described in Example 1, supra, with an on demand display. Forillustrative purposes, see FIG. 9.

To provide the on demand display to this mirror cell, a display window(with dimensions of about 7/16″×¾″) was laser-etched through anovercoating of silver/copper/paint on the rearmost (opposite,non-inward) surface of the second substrate of the mirror cell.

Over and within the display window, we applied an optical adhesive[“IMPRUV” LV potting compound (commercially available from LoctiteCorporation, Newington, Conn.)] so that a glass cover sheet, having athickness of about 0.675″, may be disposed over and affixed thereto.

The glass cover sheets suitable for use in this context were prepared bypreviously exposing a larger glass sheet to a vacuum evaporation processin which a thin film layer of silver was coated onto one of itssurfaces. The thin film layer of silver was substantially reflecting(having a reflectance of about 93%) and partially transmitting (having atransmittance of about 5%). The silver-coated glass cover sheet was thencut to size—e.g., about 1″×¾″—, and the silvered-surface disposed over,and affixed to using the optical adhesive, the display window. Over theopposite, non-silvered surface of the glass cover sheet, we placed alayer of epoxy [UV15-74R1 (commercially available from Master BondIncorporated, Hackensack, N.J.)] and affixed thereto a vacuumfluorescent display [Part No. FIP2QM8S (NEC Electronics Incorporated,Mountain View, Calif.)].

Into this mirror cell, we dispensed the electrolyte of Example 1, supra.

Example 15

In this example, we constructed an electrochromic mirror cell having thesame shape described in Example 1, supra, with an on demand display. Forillustrative purposes, see FIG. 10.

In this mirror cell, like the mirror cell of Example 14, supra, adisplay window (with dimensions of about 7/16″×¾″) was laser-etchedthrough the silver/copper/paint overcoating of the rearmost (opposite,non-inward) surface of the second substrate of the mirror cell.

A thin film layer of silver was then coated over the display window soformed by electron beam evaporation in a vacuum chamber as describedsupra. The thin film layer of silver was substantially reflecting(having a reflectance of about 90%) and partially transmitting (having atransmittance of about 8%).

Over and within the silvered-display window, we applied a layer of epoxy[UV15-74RI (Master Bond)] and affixed thereto a vacuum fluorescentdisplay [Part No. FIP2QM8S (NEC Electronics)].

Into this mirror cell, we dispensed the electrolyte of Example 1, supra.

Example 16

In this example, we constructed an electrochromic mirror cell using asthe first substrate and second substrate clear HW-ITO-coated glass. Overthe inward surface of the second substrate, we coated a layer ofchromium at a thickness of about 100 Å as an adhesion promoter. We thencoated a thin film of silver at a thickness of about 450 Å onto thelayer of chromium as a reflective element, and a layer of tungsten oxideat a thickness of about 5,800 Å over the layer of silver as anelectrochromic solid film. The first substrate and the second substratewere positioned in spaced-apart relationship to form an 88 μm interpanespacing between the coated inward surfaces of the substrates.

We placed an opaque tape on the rearmost surface of the second substratewith apertures provided therein at appropriate locations to accommodatevacuum fluorescent displays and other information indicia.

A vacuum fluorescent display was affixed to this mirror cell asdescribed in Example 14, supra, but dispensing with the reflector coatedcover sheet. The display provided compass directional information and,dependent on the vehicle direction when driving, displayed N, NE, E, SE,S, SW, W or NW when any one of which coordinates was activated bycompass circuitry included in the mirror housing and assembly into whichthe electrochromic mirror element was mounted for driving in a vehicle,and such as described in commonly assigned U.S. Pat. No. 5,255,442(Schierbeek). Turn signal indicia [JKL NEO-Wedge Lamps T2-1/4(commercially available from JKL Components Corporation, Paloina,Calif.)] were also located behind the rearmost surface of the secondsubstrate, with appropriately shaped apertures cut into the opaque tapeat the location of the turn signal indicia. The turn signal indicia wasactivated through a triggering mechanism from the particular turnsignal. For an illustration of the use of turn signal indicia 21 in anelectrochromic mirror, see FIG. 12.

Into this mirror cell, we dispensed the electrolyte of Example 1, supra.

Upon introduction of an applied potential of about 1.4 volts to themirror, we observed the high reflectance to change from about 74.1% to alow reflectance of about 7.0%. We also observed the transmittance to beabout 4.5% in the clear state.

This mirror was installed in a vehicle and tested under a variety ofactual day and night driving conditions, and was found to operate forits intended purpose.

Example 17

In this example, we constructed an electrochromic mirror suitable foruse as an interior rearview mirror for a motor vehicle.

The mirror was constructed from clear ITO-coated glass as the firstsubstrate (having a sheet resistance of about 80 ohms per square). Asthe second substrate of the mirror cell we used ordinary soda-limeglass. Both substrates were sized and shaped to identical dimensions. Anotch was cut in the middle of the top edge of the first substrate andanother notch was cut in the middle of the bottom edge of the secondsubstrate. A thin metal film bus bar was formed along the edges of thefirst substrate by first affixing a mask over the central region leavingmost of the perimeter region unmasked, and then depositing by a vacuumevaporation process a thin film of chromium having a thickness of about2,000 Å followed by a thin film of silver having a thickness of about5,000 Å.

A layer of chromium at a thickness of about 1,000 Å was coated directlyonto the inward surface of the second glass substrate as an adhesionpromoter. A thin film of silver at a thickness of about 1,000 Å was thendeposited onto the layer of chromium as a reflective element andtungsten oxide at a thickness of about 5,000 Å was then coated over thelayer of silver as an electrochromic solid film.

The first substrate and the second substrate were then positioned in aspaced-apart relationship so that the edges of the substrates were flushand a seal was applied to form a cavity between the substrates. In thisflush design, the interpane spacing between the coated inward surfacesof the substrates was 88 μm.

For this flush design interior mirror, we formulated an electrolyte asin Example 1, supra. We dispensed this electrolyte into the mirror cellusing the vacuum backfilling method [as described in Varaprasad I].

Electrical leads were then attached to the mirror. The notch in thesecond substrate permitted an electrical lead to be attached at a pointcontact on the thin metal film bus bar on the bottom edge of the firstsubstrate. Similarly, the notch in the first substrate caused a portionof the top edge of the inward surface of the second substrate to beexposed, permitting an electrical lead to be attached at a point contacton the chromium/silver/tungsten oxide coating.

Upon introduction of an applied potential of about 1.5 volts to themirror, we observed a reflectance change from a high reflectance ofabout 85.3% to a low reflectance of about 7.5%.

Example 18

In this example, we constructed an aspherical electrochromic mirror cellusing as the first substrate a 0.063″ thick clear, HW-ITO-coated glassshape and as the second substrate a 0.093″ thick clear HW-ITO-coatedglass substrate. The second substrate was silver coated on its rearsurface (i.e., the fourth surface of the assembly) using a conventionalwet chemical silverline process, as is well-known in the automotivesilvering art. The first and second substrates were individually bent toan aspheric radius using a multi-radius design commonly used fordriver-side exterior mirrors on vehicles in Europe. This design includesan inboard spherical curvature region of about 2,000 mm radius ofcurvature and a continuously reducing radius, aspherical curvatureoutboard region that decreased in radius from about 560 mm through about230 mm to about 160 mm. The bent, multi-radius substrates wereindividually press bent, as an oversized lite, in a bending press mold,as previously described, by first heating the glass to a temperature ofat least about 550° C. followed by press bending to conform to aprecision mold.

After bending and annealing the oversized multi-radius lite, themulti-radius shapes (of the size and shape used as a driver-sideexterior mirror on a Peugeot 605 vehicle manufactured by PSA of Francefor model year 1994), were cut from the oversized, bent, multi-radiuslite. The inward facing, ITO-coated surface of the second substrate wascoated with a layer of tungsten oxide of thickness about 5,500 Å, usingelectron beam evaporation and using a rapid cycle process, as previouslydescribed, whereby evaporation of the tungsten oxide commenced when,during initial pumpdown, the chamber pressure reached about 2×10⁻⁴ torr(mm Hg). The first substrate and the second substrate were positioned inspaced apart relationship to form an interpane spacing of about 88 μmbetween the coated inward facing surfaces of the substrates. The sealmaterial used was EPON 8281 epoxy that was cured with ANCAMINE® 2014FGas a latent curing agent,

To enhance uniformity and conformity of matching a local radius of thefirst substrate to its corresponding local radius on the secondsubstrate, glass beads having a diameter of about 88 μm were included inthe uncured epoxy as well as being sprinkled over the surface of theinward facing surface of the second substrate. Using a computernumerical control (“CNC”) controlled ASYMTEK dispenser and a 20 gaugeneedle, the uncured epoxy was applied around the perimeter of the inwardsurface of the first substrate. The first substrate was then carefullyaligned over the corresponding local radii of the second substrate andwas temporarily affixed thereto using simple clamps. This assembly wasplaced in a “MYLAR” vacuum bag and a vacuum was established so thatatmospheric pressure impressed upon the surfaces of the assembly toforce conformity between the local radii of the first and secondsubstrates. Next, and while under vacuum and thus still underatmospheric pressure, the vacuum bagged assembly was based in an ovenand exposed to a temperature of about 140° C. for a period of time ofabout one hour to cure the epoxy. Once cured, the assembly was removedfrom the oven, the vacuum bag was vented and removed, and the emptycell, so formed, was filled with the electrolyte of Example 1, supra,using vacuum backfilling.

Once cell fabrication was completed, we introduced a voltage of about1.4 volts to the mirror, and observed the high reflectance to changefrom about 74.7% to a low reflectance of about 7.3%. This change inreflectance was achieved rapidly and uniformly with little to no doubleimaging observed.

This mirror was mounted into a bezel, and installed in a vehicle. Themirror was found to operate for its intended purpose.

Also, such mirrors showed the environmental, cycle and performanceresilience described supra.

Example 19

In this example, we constructed a multi-radius mirror, similar to thatdescribed in Example 18, supra. However, in this example the secondsubstrate was non-ITO coated clear glass, and not silverline mirrored onits fourth surface. Instead, its inward facing plain glass surface wasfirst coated with a layer of chromium (adhesion promoter layer) having athickness of about 1,000 Å, followed by a layer of aluminum (reflector)having a thickness of about 2,000 Å, and followed by a layer of tungstenoxide (electrochromic solid film) having a thickness of about 6,000 Å.

Once cell fabrication was completed, we introduced a voltage of about1.4 volts to the mirror and observed the high reflectance to change fromabout 69.7% to a low reflectance of about 6.4%. This change inreflectance was achieved rapidly and uniformly with little to no doubleimaging observed.

Example 20

The mirror of this example was fabricated generally as described inExample 3, supra, except that the front substrate was a flatHW-ITO-coated glass shape having a thickness of about 0.043″, withdimensions of about 6.75″×12.7″. In addition, the rear substrate wasflat, plain glass having a thickness of 0.063″ with similar dimensions.The interpane spacing in this mirror construction was about 74 microns.The electrolyte comprised lithium perchlorate (about 0.01 M), lithiumtetrafluoroborate [about 0.04 M), ferrocene (about 0.04 M) and “UVINUL”400 (about 5% (w/v)] dissolved in a solvent combination oftetramethylene sulfone and propylene carbonate [in a ratio of about60:40 (v/v)]. The electrochromic mirror cell so formed was suitable foruse in an exterior mirror assembly on a large, Class 8, Kenworth T600heavy truck manufactured by Kenworth Truck Company, Seattle, Wash.

Once cell fabrication was completed, we introduced a voltage of about1.4 volts to the mirror (using around-the-perimeter bus bars), andobserved the high reflectance to change from about 81.2% to a lowreflectance of about 16.5%. This change in reflectance was achievedrapidly and uniformly with little to no double imaging observed.

Example 21

In this example, we report results of rearview mirror constructionsotherwise similar to that described in Example 1, supra, except for theuse of tungsten oxide doped with tin instead of undoped tungsten oxide.Electrochromic solid films of the tin doped tungsten oxide type weredeposited both by physical vapor deposition [specifically, electron beamevaporation) and by non-vacuum deposition (specifically, by wet chemicaldeposition with the dip/fire technique, see U.S. Pat. No. 4,855,161(Moser)].

In the physical vapor deposition approach, the procedure andconstruction described in Example 1, supra, was used but withevaporation of a mixture of tungsten oxide/tin oxide (in a ratio ofabout 95:5% w/w) to form a tin-doped tungsten oxide having a thicknessof about 6,000 Å (with the Sn/WO₃ weight ratio in the coating at about0.04). Rearview mirror cells so formed using such evaporated tin dopedtungsten oxide were tested and operated to determine their suitabilityfor use as rearview mirrors in automobiles. These mirrors were found tobe suitable both in terms of performance and in terms ofcycle/environmental resilience.

Compared to similar mirror cells fabricated using undoped tungstenoxide, but without other intended differences, tin doping of thetungsten oxide film produced a noticeably more neutral coloration whenthe mirrors were electrochromically dimmed under applied potential.Also, we found that mixing of tin oxide with the tungsten oxide duringits reactive evaporation under vacuum led to less spitting from theevaporation crucible and facilitated, perhaps due to enhanced electricalconductivity in the inorganic oxide mixture, easier evaporation of themixture to form the oxide film on the glass. This enhances ease ofmanufacturing of electrochromic devices using, for example, a vacuumdeposited, tungsten oxide-based electrochromic film, and the like. Wealso observed a higher bleached state % reflectivity and a faster bleachtime when tin doped tungsten oxide was used compared to undoped tungstenoxide.

In the non-vacuum deposition approach, a wet chemical, dip/fire methodwas used, such as is described in U.S. Pat. No. 4,855,161 (Moser), thedisclosure of which is hereby incorporated herein by reference. Adipping solution was prepared which comprised about 7.5 wt % tungstenhexachloride, about 2.5 wt % dibutyltin oxide, about 55 wt % ethylacetate, about 30 wt % isopropanol and about 5 wt % methanol. HW-ITOcoated glass substrates were coated with this sol-gel formulationdipping solution by a conventional dip-coating method, and transferredto an oven pre-heated to a temperature of about 120° C. In the oven, theas-dipped coating, having already been air dried, was fired for a periodof time of about 2 hours to produce the desired tin doped tungsten oxidecoating, with the Sn/WO₃ weight ratio being about 0.25.

Again, rearview mirrors cells were constructed as described in Example1, supra, except that this dip/fire tin doped tungsten oxide coating wasused.

The performance characteristics of such rearview mirrors are reported inTables VI(a) and VI(b) below:

TABLE VI(a) Room Temperature, 1.5 V, 5 secs/5 secs cycle Number ofTransition Times (secs) Cycles % HR % LR 70-20% 10-60% Initial 79.7 9.55.3 5.9 25,000 76.6 9.3 5.1 5.2 50,000 77.0 8.9 4.8 4.9 80,000 76.2 8.94.7 4.7 120,000 76.0 8.7 4.7 4.4

TABLE VI(b) 50° C., 1.5 V, 5 secs/5 secs cycle Number of TransitionTimes (secs) Cycles % HR % LR 70-20% 10-60% Initial 78.7 8.0 4.7 6.225,000 77.2 8.2 4.6 5.6 50,000 77.6 8.1 4.6 5.2 80,000 76.6 7.7 4.7 5.4120,000 75.5 8.1 4.4 5.2

Sol-gel formulations dipping formulations with different Sn/WO₃ weightratios were coated on transparent conductor coated glass substrates. Wefound desirable a coating with a ratio between about 0.1 and about 0.5.Different firing temperatures were also used, and we found desirable afiring temperature within the range of about 120° C. and 300° C.

Example 22

In this example, we constructed a continually variable transmissionbandpass filter. The spectral content passed by a bandpass filter may beelectrically attenuated and thus provide user control over not just thespectral content of radiation (typically, a spectral sub-region band ofvisible, ultraviolet, near-infrared or infrared electromagneticradiation), but also over the intensity of the radiation passed by thefilter. Such bandpass filters are typically of the interference typecomprising multiple thin film layers of determined thickness andrefractive index so as to selectively transmit (and occasionallyreflect) radiation such as incident light. Such interference filtershave wide applications, such as in the diagnosis of disease (by tracingof fluorescent antibodies), spectral radiometry and colorimetry.Continually variable transmissive and reflective filters are useful inoptical filters, display devices including heads-up display devices, thecontrol of automotive lighting sources including headlamps, controlenhancement filters, laser optic systems and similar applications. Suchvariable intensity filters are preferably medium-band, narrow-band orrestricted band filters that permit isolation of wavelength intervalswith a bandwidth as low as a few nanometers (such as, less than about100 nanometers, and in some applications less than about 10 nanometersin more spectrally selective applications) without requiring use ofdispersion elements (such as prisms and gratings), but with electricallycontrollable modulation of the intensity of light or other radiationwhich passes therethrough and/or reflects therefrom.

As an example of such a variable intensity filter, we constructed anelectrochromic window element having dimensions of about 2″×2″, such asis described in Example 5, supra, and attached to the outermost glasssurface thereof a 600 nm medium-band interference filter having abandwidth of about 40 nm, whose % transmission versus wavelength (nm)spectrum is shown as solid curve X in FIG. 17. This filter was fixed tothe glass of the electrochromic window cell using an index matchingoptical adhesive having an index of about 1.5.

A plot of % transmission versus wavelength for this continuouslyvariable intensity filter is shown in FIG. 17 for voltages applied tothe electrochromic medium within the range of from about 0 volts toabout 1.4 volts. In FIG. 17, light transmission through the band passfilter and the electrochromic window cell with no potential applied isrepresented by curve A. At an applied potential of about 0.3 volts,light transmission through the band pass filter and the electrochromicwindow cell is represented by curve B. At an applied potential of about0.5 volts, light transmission through the band pass filter and theelectrochromic window cell is represented by curve C. At an appliedpotential of about 0.8 volts, light transmission through the band passfilter and the electrochromic window cell is represented by curve D. Atan applied potential of about 1.1 volts, light transmission through theband pass filter and the electrochromic window cell is represented bycurve E. And at an applied potential of about 1.4 volts, lighttransmission through the band pass filter and the electrochromic windowcell is represented by curve F. In Table VII below, then transmission atabout 600 nanometers is presented in connection with the voltage appliedto the variable intensity filter.

TABLE VII Applied Voltage % transmission at about (volts) 600 nm 0 470.3 42 0.5 35 0.8 25 1.1 17 1.4 9

As seen in FIG. 17, the spectral selectivity is substantially preservedas the light intensity is modulated continuously under a potentialvariably applied to the electrochromic medium.

Rather than attaching a separate filter to an electrochromic cell asdescribed above, an alternative approach is to deposit an interferencestack of thin film coatings on at least one surface of the substrates inthe electrochromic cell. In such an arrangement, the transparentconductor and a metal oxide electrochromic solid film layer may comprisein combination with other dielectric, semi-conductor and conductinglayers, the interference stack that provides spectral selectivity.

Example 23

The electrochromic mirror cell of this example was constructed asdescribed in Example 4, supra, except that the electrolyte included AMPTas a redox promoter in place of the redox promoter, phenothiazine. AMPTwas synthesized following the procedures described in U.S. Pat. No.4,666,907 (Fortin), the disclosure of which is hereby incorporatedherein by reference.

The synthesized AMPT was purified by recrystallization from methanol.

The elemental analysis of the AMPT was determined to be:

C H N S 0 Calculated (%) 66.40 4.83 5.16 11.82 11.70 Found (%) 66.554.76 5.19 12.19 11.30

The electrolyte comprised AMPT (about 0.035 M), ferrocene (about 0.02M), lithium perchlorate (about 0.055 M) and “UVINUL” 400 [about 5%(w/v)] dissolved in propylene carbonate. Performance of the filledelectrochromic mirror cell is reported in Table VIII below:

TABLE VIII 50° C., 1.3 V, 15 sec/15 sec cycle Number Transition Times(seconds) of Cycles % HR % LR 70-20% 60-20% 10-60% 10-50% Original 74.66.7 3.5 3.1 13.6 7.6 65,000 71.4 8.4 4.1 3.6 5.1 3.6

Example 24

The electrochromic mirror cell of this example was constructed asdescribed in Example 3, supra, except that the electrolyte included C-PTas a redox promoter in place of the redox promoter, phenothiazine. C-PTwas synthesized following the procedures described in N. L. Smith, J.Org. Chem., 15, 1125 (1950).

In this example, the substrates were juxtaposed flush to each other andan around-the-perimeter evaporated bus bar (comprising about 1,000 Å ofchromium metal) was evaporatively deposited, using a mask to mask offthe central portion, around the edge perimeter of the inward facingsurface of the first ITO-coated substrate followed by another 10,000 Åof silver metal evaporated thereover. A chromium adhesion layer/silverreflector layer/tungsten oxide electrochromic solid film layer wasevaporated onto the opposing surface of the second substrate, which wasplain glass. The electrolyte comprised C-PT (about 0.05 M), lithiumperchlorate (about 0.05 M) and “UVINUL” 400 [about 5% (w/v)] dissolvedin propylene carbonate.

With a potential of about 1.3 volts applied between the evaporated busbar around the perimeter of the inward facing surface of the firstsubstrate and the metal reflector layer on the opposing secondsubstrate, we observed the initial high reflectivity state [HR (%)] tobe about 87.3%, which dimmed to a low reflectivity state [LR (%)] ofabout 7.2%, with the transition from 70 to 20% reflectance occurring ina period of time of about 2.1 seconds and the transition from 10 to 60%reflectance, upon bleaching by shorting the electrodes, occurring in aperiod of time of about 7.1 seconds.

Example 25

In this example, we constructed an electrochromic mirror suitable foruse as an interior rearview mirror for a motor vehicle. Construction wasotherwise similar to that described in Example 6, supra, except that theshape of the mirror constructed for this example was of the size andshape commonly used for interior rearview mirrors. In addition, thefirst substrate was glass coated with a layer of ITO having a thicknessof about 300 Å, with a specific resistivity of about 2.4×10⁻⁴ohm.centimeter and a sheet resistance of about 80 ohms per square. Also,a thin film of aluminum having a thickness of about 2,000 Å was used asa reflective element instead of the silver reflective element used inthe construction of Example 6, supra.

We filled the electrochromic rearview mirror with an electrolytecomprising ferrocene (about 0.015 M), phenothiazine (about 0.06 M),lithium perchlorate (about 0.05 M) and “UVINUL” 400 [about 5% (w/v)] ina solvent combination of propylene carbonate and tetramethylene sulfone[in a ratio of about 50:50 (v/v].

With about 1.1 to about 1.4 volts applied between the wrap-around silverconductive frit bus bar on the perimeter of the ITO-coated, inwardfacing surface on the first substrate and the aluminumreflector/chromium adhesion layer combination on the opposing surface ofthe second substrate, the electrochromic rearview mirror was observed todim from a high reflectivity state of about 70%±5% reflectance to adimmed state of about 6%±2% reflectance.

The electrochromic mirror of this example was tested and demonstrated tomeet the requirements for commercial use on vehicles, as both interiorrearview mirrors and exterior rearview mirrors. Also, in terms of cyclestability, an electrochromic mirror (which initially demonstrated a highreflectivity state of about 70.5% reflectance, and which dimmed to areflectivity of about 7.1% reflectance when a potential of about 1.4volts was applied thereto) was repetitively cycled at a temperature ofabout 50° C. for a total of 39,463 cycles, with each cycle consisting ofthe introduction of an applied potential of about 1.4 volts for 15seconds and an applied potential of zero volts for 15 seconds. Aftercycling was completed, the mirror retained a high reflectivity state ofabout 68.2% reflectivity, dimmed to about 6.6% reflectivity under anapplied potential of about 1.4 volts, and continued to be suitable foruse on vehicles. Also, after about 14 days of oven bake at a temperatureof about 85° C., a mirror (which initially had a high reflectivity stateof about 71.6% reflectance, and which dimmed to about 7.4% reflectancewhen an applied potential of about 1.4 volts was introduced thereto)exhibited a high reflectivity state of about 76.1% reflectance anddimmed to about 8.5% reflectance when about 1.4 volts was appliedthereto. This mirror continued to be suitable for its intended use onvehicles even after oven bake at 85° C. This mirror satisfied theperformance requirements and reliability requirements, such as ofautomobile manufacturers, to be suitable for use within the interiorcabin of an automobile, or for use as an exterior mirror.

These examples are provided for illustrative purposes only, and it willbe clear to those of ordinary skill in the art that changes andmodifications may be practiced within the spirit of the claims whichdefine the scope of the present invention. Thus, the art-skilled willrecognize or readily ascertain using no more than routineexperimentation, that equivalents exist to the embodiments of theinvention described herein. And, it is intended that such equivalents beencompassed by the claims which follow hereinafter.

1. A signal mirror for a vehicle comprising: a reflective mirror elementhaving a front side and a rear side; said reflective mirror elementcomprising a semitransparent mirror reflector coated onto alight-transmitting substrate; wherein visible light transmission throughsaid reflective mirror element is at least about 3% visible lighttransmission; wherein visible light reflectance by said reflectivemirror element is at least about 40% visible light reflectance forvisible light incident upon the front side of said reflective mirrorelement; wherein said reflective mirror element does not exhibitsubstantial spectral selectivity in its reflectance of visible lightincident upon the front side of said reflective mirror element andwherein said reflective mirror element does not exhibit substantialspectral selectivity in its transmission of visible light incident uponthe rear side of said reflective mirror element; said semitransparentmirror reflector comprising a metal thin film layer, wherein said metalthin film layer is overcoated with an overcoating layer and wherein atleast one of (a) said overcoating layer comprises another metal thinfilm layer of visible light reflectance higher than that of said metalthin film layer, (b) said overcoating layer comprises a transparentelectrically conductive metal oxide layer, (c) said metal thin filmlayer is undercoated with an undercoating layer, (d) said metal thinfilm layer is undercoated with an undercoating layer comprising atransparent electrically conductive metal oxide layer and (e) said metalthin film layer is undercoated with an undercoating layer comprising atransparent indium thin oxide conductive metal oxide layer having alayer thickness of at least about 50 angstroms; and at least one of (a)a turn signal light display that emits visible light upon actuation of aturn signal by a driver of a vehicle equipped with said reflectivemirror element, said turn signal light display disposed to the rear ofthe rear side of said reflective mirror element and configured so thatsaid light emitted by said turn signal light display passes through saidmetal thin film layer of said semitransparent mirror reflector to beviewed by a viewer viewing from the front of said reflective mirrorelement and wherein said turn signal light display exhibits, whenelectrically powered and when operated in the vehicle during daytimedriving conditions, a display luminance of at least about 30 footlamberts as measured with said turn signal light display placed behind,and emitting light through, said reflective mirror element and (b) ablind-spot indicator light display that emits visible light upon adetection by a blind-spot detector that is part of a vehicle equippedwith said blind-spot indicator light display, said blind-spot indicatorlight display disposed to the rear of the rear side of said reflectivemirror element and configured so that said light emitted by saidblind-spot indicator light display passes through said metal thin filmlayer of said semitransparent mirror reflector to be viewed by a viewerviewing from the front of said reflective mirror element and whereinsaid blind-spot indicator light display exhibits, when electricallypowered and when operated in the vehicle during day time drivingconditions, a display luminance of at least about 30 foot lamberts asmeasured with said blind-spot indicator light display placed behind, andemitting light through, said reflective mirror element.
 2. The signalmirror of claim 1, wherein said metal thin film layer comprises a metalselected from the group consisting of aluminum, palladium, platinum,molybdenum, titanium, chromium, silver, nickel and iron, and whereinsaid metal thin film layer has a layer thickness in the range from about200 angstroms to about 750 angstroms.
 3. The signal mirror of claim 2,wherein said reflective mirror element comprises a large area vehicularexterior rearview reflective mirror element having an area greater thanabout 140 square centimeters and wherein said metal thin film layer isformed by sputtering in a vacuum deposition process.
 4. The signalmirror of claim 1, wherein said visible light reflectance by saidreflective mirror element is in the range from about 40% visible lightreflectance to about 80% visible light reflectance for visible lightincident upon the front side of said reflective mirror element, andwherein, when not emitting light, the disposition of said at least oneof a turn signal light display and a blind-spot indicator light displayto the rear of said reflective mirror element is not substantiallydistinguishable to the driver of a vehicle equipped with said reflectivemirror element, and wherein said metal thin film layer is formed bysputtering in a vacuum deposition process.
 5. A signal mirror for avehicle comprising: a reflective mirror element having a front side anda rear side; said reflective mirror element comprising a semitransparentmirror reflector coated onto a light-transmitting substrate; whereinvisible light transmission through said reflective mirror element is atleast about 3% visible light transmission; wherein visible lightreflectance by said reflective mirror element is at least about 40%visible light reflectance for visible tight incident upon the front sideof said reflective mirror element; wherein said reflective mirrorelement does not exhibit substantial spectral selectivity in itsreflectance of visible light incident upon the front side of saidreflective mirror element and wherein said reflective mirror elementdoes not exhibit substantial spectral selectivity in its transmission ofvisible light incident upon the rear side of said reflective mirrorelement; said semitransparent mirror reflector comprising a metal thinfilm layer, wherein said metal thin film layer is undercoated with anundercoating layer and wherein at least one of (a) said undercoatingcoating layer comprises another metal thin film layer of visible lightreflectance lower than that of said metal thin film layer, (b) saidundercoating layer comprises a transparent electrically conductive metaloxide layer, (c) said undercoating layer comprising a transparentelectrically conductive indium tin oxide layer having a layer thicknessof at least about 50 angstroms and (d) said undercoating layercomprising a transparent electrically conductive indium tin oxide layerhaving a layer thickness of at least about 50 angstroms and less thanabout 300 angstroms; and at least one of (a) a turn signal light displaythat emits visible light upon actuation of a turn signal by a driver ofa vehicle equipped with said reflective mirror element, said turn signallight display disposed to the rear of the rear side of said reflectivemirror element and configured so that said light emitted by said turnsignal light display passes through said metal thin film layer of saidsemitransparent mirror reflector to be viewed by a viewer viewing fromthe front of said reflective mirror element and wherein said turn signallight display exhibits, when electrically powered and when operated inthe vehicle during day time driving conditions, a display luminance ofat least about 30 foot lamberts as measured with said turn signal lightdisplay placed behind, and emitting light through, said reflectivemirror element and (b) a blind-spot indicator light display that emitsvisible light upon a detection by a blind-spot detector that is part ofa vehicle equipped with said blind-spot indicator light display, saidblind-spot indicator light display disposed to the rear of the rear sideof said reflective mirror element and configured so that said lightemitted by said blind-spot indicator light display passes through saidmetal thin film layer of said semitransparent mirror reflector to beviewed by a viewer viewing from the front of said reflective mirrorelement and wherein said blind-spot indicator light display exhibits,when electrically powered and when operated in the vehicle during daytime driving conditions, a display luminance of at least about 30 footlamberts as measured with said blind-spot indicator light display placedbehind, and emitting light through, said reflective mirror element. 6.The signal mirror of claim 5, wherein said metal thin film layer has alayer thickness of at least about 200 angstroms and a reflectivity of atleast about 40% visible light reflectance for visible light incidentthereon.
 7. The signal mirror of claim 6, wherein said metal thin filmlayer comprises a metal selected from the group consisting of aluminum,palladium, platinum, molybdenum, titanium, chromium, silver, nickel andiron.
 8. The signal mirror of claim 6, wherein said metal thin filmlayer comprises silver.
 9. The signal mirror of claim 8, wherein saidreflective mirror element comprises a portion of an electrochromicmirror, and wherein said electrochromic mirror comprises anelectrochromic medium disposed in a cavity between a front substantiallylight transmitting substrate and a rear substrate, said frontsubstantially light transmitting substrate having a front surface, saidfront substantially light transmitting substrate further having a rearsurface that is coated with a transparent electrically conducting layer,said front substantially light transmitting substrate spaced-apart fromsaid rear substrate and wherein said rear substrate comprises saidreflective mirror element, and wherein said semitransparent mirrorreflector of said reflective mirror element is disposed on the surfaceof the rear substrate closest to the transparent electrically conductingcoated rear surface of said front substrate and wherein saidelectrochromic medium disposed in said cavity between said frontsubstrate and said rear substrate comprising said reflective mirrorelement contacts said semitransparent mirror reflector, and wherein saidelectrochromic mirror reflects at least about 55% of visible lightincident at said front surface of said front substantially lighttransmitting substrate when said electrochromic medium is in itsbleached state and wherein said electrochromic mirror does not exhibitsubstantial spectral selectivity in its reflectance of visible lightincident at said front surface of said front substantially lighttransmitting substrate when said electrochromic medium is in itsbleached state, and wherein said electrochromic mirror transmits atleast about 4% of visible light incident at the rear of said rearsubstrate when said electrochromic medium is in its bleached state andwherein said electrochromic mirror does not exhibit substantial spectralselectivity in its transmission of visible light passing therethroughwhen said electrochromic medium is in its bleached state.
 10. A signalmirror for a vehicle comprising: a reflective mirror element having afront side and a rear side; said reflective mirror element comprising asemitransparent mirror reflector coated onto a light-transmittingsubstrate, wherein said reflective mirror element comprises a portion ofan exterior electrochromic mirror, and wherein said electrochromicmirror comprises an electrochromic medium disposed in a cavity between afront substrate and said reflective mirror element, and wherein saidelectrochromic medium disposed in said cavity between said frontsubstrate and said reflective mirror element contacts saidsemitransparent mirror reflector; wherein visible light transmissionthrough said reflective mirror clement is at least about 3% visiblelight transmission; wherein visible light reflectance by said reflectivemirror element is at least about 40% visible light reflectance forvisible light incident upon the front side of said reflective mirrorelement; wherein said reflective mirror element does not exhibitsubstantial spectral selectivity in its reflectance of visible lightincident upon the front side of said reflective mirror element andwherein said reflective mirror element does not exhibit substantialspectral selectivity in its transmission of visible light incident uponthe rear side of said reflective mirror element; said semitransparentmirror reflector comprising a metal thin film layer; and at least one of(a) a turn signal light display that emits visible light upon actuationof a turn signal by a driver of a vehicle equipped with said reflectivemirror element, said turn signal light display disposed to the rear ofthe rear side of said reflective mirror element and configured so thatsaid light emitted by said turn signal light display passes through saidmetal thin film layer of said semitransparent mirror reflector to beviewed by a viewer viewing from the front of said reflective mirrorelement and wherein said turn signal light display exhibits, whenelectrically powered and when operated in the vehicle during day timedriving conditions, a display luminance of at least about 30 footlamberts as measured with said turn signal light display placed behind,and emitting light through, said reflective mirror element and (b) ablind-spot indicator light display that emits visible light upon adetection by a blind-spot detector that is part of a vehicle equippedwith said blind-spot indicator light display, said blind-spot indicatorlight display disposed to the rear of the rear side of said reflectivemirror element and configured so that said light emitted by saidblind-spot indicator light display passes through said metal thin filmlayer of said semitransparent mirror reflector to be viewed by a viewerviewing from the front of said reflective mirror element and whereinsaid blind-spot indicator light display exhibits, when electricallypowered and when operated in the vehicle during day time drivingconditions, a display luminance of at least about 30 foot lamberts asmeasured with said blind-spot indicator light display placed behind, andemitting light through, said reflective mirror element.
 11. The signalmirror of claim 10, wherein said at least one of a turn signal lightdisplay and a blind-spot indicator light display exhibits, whenelectrically powered and when operated in the vehicle during day timedriving conditions, a display luminance of at least about 80 footlamberts as measured with the light display placed behind, and emittinglight through, said electrochromic medium and with said electrochromicmedium in its bleached state, and wherein said electrochromic mediumcomprises a solid-phase at least partially formed in situ in said cavityby a polymerization reaction.
 12. The signal mirror of claim 10, whereinthe substrate thickness of one of said front substrate and saidreflective mirror element is thinner than the substrate thickness of theother of said front substrate and said reflective mirror element, andwherein the substrate thickness of said one of said front substrate andsaid reflective mirror element is about 0.043″, and wherein thesubstrate thickness of said other of said front substrate and saidreflective mirror element is about 0.063″, and wherein said reflectivemirror element comprises a large area vehicular exterior rearviewreflective mirror element having an area greater than about 140 squarecentimeters.
 13. The signal mirror of claim 10, wherein said at leastone of a turn signal light display and a blind-spot indicator lightdisplay comprises at least one light emitting diode and wherein saidmetal thin film layer has a layer thickness of at least about 200angstroms.